Hello Everyone!
Let's tackle this question, one thing at a time, and narrow it down to the correct choice quickly! Here is the original question, with the major differences between each option highlighted in orange:
Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.
(A) has been dated to be 3.47 billion years old and thus is
(B) has been dated at 3.47 billion years old and thus
(C) have been dated to be 3.47 billion years old and thus are
(D) have been dated as being 3.47 billion years old and thus
(E) have been dated at 3.47 billion years old and thus are
After a quick glance over the options, there are a few places we can focus on to narrow down our choices:
1. has been vs. have been (Subject-Verb Agreement)
2. dated to be / at / as being (Idioms)
3. thus is / thus / thus are (Subject-Verb Agreement / Meaning)
Let's start with #1 on our list because it will eliminate 2-3 options right away. This is a matter of subject-verb agreement! If we look closely at the original sentence, we can find the subject:
Rock samples taken from the remains of an asteroid about twice the size of the 6-mile-wide asteroid that eradicated the dinosaurs has been dated to be 3.47 billion years old and thus is evidence of the earliest known asteroid impact on Earth.
We see that the subject "rock samples" is plural, which means we need to use a plural verb to match:
(A) has been dated to be 3.47 billion years old and thus is
(B) has been dated at 3.47 billion years old and thus
(C) have been dated to be 3.47 billion years old and thus are
(D) have been dated as being 3.47 billion years old and thus
(E) have been dated at 3.47 billion years old and thus are
We can eliminate options A & B because they use a singular verb with a plural subject, which doesn't match.
Now that we have it narrowed down to only 3 options, let's tackle #2 on our list: idiom structure. Whenever we say that an item is "dated" a certain age, there is a particular way to word it. We typically say that something is "dated at" a certain age! Let's take a closer look:
(C) have been dated to be 3.47 billion years old and thus are --> not idiomatically correct = WRONG
(D) have been dated as being 3.47 billion years old and thus --> not idiomatically correct = WRONG
(E) have been dated at 3.47 billion years old and thus are --> idiomatically correct = CORRECT
There you have it - option E is the correct choice! It's the only one that uses proper subject-verb agreement and proper idiom formatting!
Don't study for the GMAT. Train for it.
