The domesticated camel, which some scholars date around the twelfth ce

I found the below explanation is very good and thought of sharing with you.
( I found this notes on the internet-- I don't remember)

The domesticated camel, which some scholars date around the twelfth century B.C., was the key to the development of the spice trade in the ancient world.

a. The domesticated camel, which some scholars date
b. The domesticated camel, which some scholars have thought to occur
c. Domesticating the camel, dated by some scholars at
d. The domestication of the camel, thought by some scholars to have occurred
e. The camel's domestication, dated by some scholars to have been

In D, it seems that "thought by some scholars..." modifies camel, rather than domestication Okay, I checked out the other topic, and there was no explanation of the answer. Okay, to be honest, I didn't catch the mistake in E the very first time I read the question, either. I picked D, because somehow it sounded better, but I wasn't sure why.

Later, when a student asked me specifically what was wrong with E, I looked at the
question a little more carefully. E has a classic mistake, albeit a well disguised one!
I teach this mistake frequently in my SAT II classes for high school students. Let me
show you an example of what my high school students might write:

The greatest change in my life was when I immigrated to the US.

Can you see the mistake in this sentence?

Let me try again, with a little hint:

The greatest change in my life was when I immigrated to the US.

Can you see it now?

Okay, just in case, let me give you one more sentence (I'm pretty much doing now
what I do in class to explain this grammar point.)

"Target Team Member" to TestMagician:

This pen is a bargain because it's only ten cents.

Hint again:

This pen is a bargain because it is only ten cents.

Okay, got it yet?

Let's work backward. The last sentence is incorrect because it is incorrectly saying
that the pen and the ten cents are the same thing; a pen cannot be ten cents; it can
be a writing instrument, it can be a bargain, it can even be a weapon in some cases,
but it cannot be ten cents. One-tenth of a dollar is ten cents, a dime is ten cents, but
a pen is not.

Are you getting it? Probably, but since I've already started, please let me finish...

Okay, now let's look at the immigration sentence:

The greatest change in my life was when I immigrated to the US.

This sentence means that "change" and "when I immigrated..." are the same thing;
they in fact are not.

Like I said, this is a classic mistake, and the classic correction is:
The greatest change in my life occurred/happened when I immigrated to the US.
(Do you see where I'm heading now???)

So, in our original question, E says: The camel's domestication was around the twelfth century B.C....

GMAT cleverly hides this mistake by using "to have been" instead of a simple beverb,
but "to have been" is one of the many variants of was, were, is, are, am, etc.
The funny thing is that GMAT uses the classic correction as well:
domestication... occurred... when...

Finally, I just have to comment: I imagine that if GMAT had to explain this grammar
point, they would say in their typical, cryptic fashion something like this:
E incorrectly uses an adverb clause as the noun complement of the subject
"domestication."

Okay, what have we learned???

This:

NOUN + BE-VERB + NOUN/ADJECTIVE

For example:
The change was good for me.
The change was a good one for me.
The change was an important step for me in my life.

BUT NEVER
The change was when I came to the US.
In other words, noun complements (the words that come after a be-verb and modify
nouns) should only be nouns or adjectives (although we often use adverbs when we
want to describe location, but more on that later, if you like; this explanation is
getting pretty long!!).

I think that's it. I hope what I've said makes sense and is clear, but please be sure to
post back with questions or doubts!!

There is another question on this pattern
Madagascar was one of the last habitable areas of the earth to undergo human settlement, which has made it an ideal site for researching rare flora and fauna.
(A) Madagascar was one of the last habitable areas of the earth to undergo human settlement, which has made it
(B) Madagascar was one of the last habitable areas of the earth to have undergone human settlement, and that has made it
(C) Madagascar underwent human settlement as one of the last habitable areas of the earth, which makes it
(D) Madagascar, one of the last habitable areas of the earth, underwent human settlement, making it
(E) Because Madagascar was one of the last habitable areas of the earth to undergo human settlement, it is
The fact that madagascar was one of the last areas to be inhabited made it ideal. So which and that in A,B and C incorrectly refer to human settlement and are not correct. D also uses zerund and modifies human settlement. So E is correct.