Reading Comprehension

While atomism, a natural philosophy common to
numerous ancient traditions including Jainism and Greek
metaphysics, revolves around an idea of the atom
fundamentally similar to our unit of modern physics, the
(5) philosophical apprehension of the term is altogether
more abstract. While the philosophical atom can have any
number of qualities, such as infinitesimal size,
indestructibility, immutability, and instantaneous
existence, it is almost intrinsically unlike the
(10) physical atom, whose characteristics have been the
object of progressive precision throughout the history
of science, in that its actual physical makeup is in a
sense immaterial. Briefly put, the metaphysical atom is
the basic indivisible unit of existence, not just of matter;
(15) the natural world as perceived by an atomist consists of
nothing but atoms and void, the former traveling through
the latter and coupling with each other in a series of
productive collisions that result in the world's
various macroscopic substances. True atomism holds that
(20) there is nothing else in the world: composite objects
such as plants and planets actually do not exist,
leading the atomist position down a path that seems to
end in nihilism-accounting for the difficulty many
philosophers have had historically in espousing it.
(25) (Simples theory eventually emerged as a counterpart to
atomism that granted ontological validity to objects qua
confederations of atoms.) Interestingly, the divergence
between physical and philosophical atoms only truly came
about in the twentieth century with the discovery of
(30) subatomic particles, prior to which chemists and
physicists viewed the atom in accordance with its
etymology-the Greek a-tomos literally means "not
cuttable."

The primary focus of the passage is best described as:

(A)The common origins of philosophical and physical atomism
(B)Two ontological outlooks and their divergent concepts of the atom
(C)The relationship of atomism to belief systems like Jainism and nihilism
(D)The ways in which physics and philosophy differ in their study of existence
(E)What the atom represents to atomists rather than what it means to scientists

IMO (E)

OA [spoiler](B)[/spoiler]

Please explain....