Reading Comprehension

There can be nothing simpler than an elementary particle: it is an indivisible shard of matter, without internal structure and without detectable shape or size. One might expect commensurate simplicity in the theories that describe such particles and the forces through which they interact; at the least, one might expect the structure of the world to be explained with a minimum number of particles and forces. Judged by this criterion of parsimony, a description of nature that has evolved in the past several years can be accounted a reasonable success. Matter is built out of just two elementary particles: the classes leptons, such as electrons, and the quarks, which make up protons,neutrons, and many related particles. Four basic forces act between the elementary particles. Gravitation and electromagnetism have long been familiar in the macroscopic world; the weak force and the strong force are observed only in sub-nuclear events.

An understanding of nature at this level is a remarkable achievement; nevertheless, it is possible to imagine what an even simpler theory might be like. Ideally, the two classes of elementary particles would be collapsed into one. Similarly, one force, rather than four, might explain all the particles' interactions. An ambitious new theory now promises at least a partial unification along these lines. The theory does not embrace gravitation, which is by far the feeblest of the forces and may be fundamentally different from the others. If gravitation is excluded, however, the theory unifies all elementary particles and forces.

The first step in constructing the unified theory was demonstrating that the weak, the strong, and the electromagnetic forces could all be described by theories of the same general type. During this development, a deep connection was discovered between the weak force and electromagnetism, a connection that hinted at still grander synthesis. The new theory incorporated the leptons and the quarks into a single family and showed that one type of particle can transform into the other. At the same time the weak, the strong, and the electromagnetic forces are understood as aspects of a single underlying force. Thus, the theory is a model of frugality.

According to the passage, which of the following is true of quarks?
I. They are the elementary building blocks of neutrons.
II. Scientists have described them as having no internal structure.
III. Some scientists group them with leptons in a single class of particles.

A. I only
B. III only
C. I and II only
D. II and III only
E. I, II, and III

OA is E


In above passage, it is mentioned that

Matter is built out of just two elementary particles: the classes leptons and the quarks
classes leptons: examples electrons, and
the quarks consist of protons,neutrons, and many related particles.

Now coming back to statement I of the question.
quarks are the elementary building blocks of neutrons.
this means the neutrons are made of quarks right opposing above given statement.
Please clarify?

In above passage, it is mentioned that

Matter is built out of just two elementary particles: the classes leptons and the quarks
classes leptons: examples electrons, and
the quarks consist of protons,neutrons, and many related particles.

Now coming back to statement I of the question.
quarks are the elementary building blocks of neutrons.
this means the neutrons are made of quarks right opposing above given statement.
Please clarify?

The passage does not say that quarks consist of neutrons. The passage says that matter is "built out of...quarks" and that quarks "make up" neutrons. So while maybe on it's own the statement "quarks, which make up protons, neutrons and many related particles" could be considered slightly ambiguous, maybe, when that statement is combined with the prior statement, "built out of...quarks" what's conveyed is that neutrons are built out of quarks, which agrees with Statement I of the question.