lalabee wrote:"He is one of the persons who make money."

however, in the Verbal notes by Sumit:

"To figure out whether the quantifier is singular or plural, we need to check one more thing...
Sometimes, a quantifier refers only to one thing, not many things. For example,
each, every, and one always refer to one thing, but 10%, half, all, and most would refer to more than one thing if the object of the preposition is count (with one possible exception that I will show you in a second).

Of course, if the quantifier is always singular, then the verb must always be singular, too. (Let's not forget our common sense in grammar, okay??) For example, we say:
• One of the people is...
• Each of the students is...

Let's start with "He is one of the persons who make money."

We use the plural "make" in this sentence because "who make money" is part of the description of "people" and not directly related to "he". The singular verb "is" has already been attached to "he".

Looking at the question you posted, we have:

"Scientists say that each of the photographs taken of X by Y indicate... "

As always, we want to ignore the non-essential parts of the sentence when matching up subjects and verbs. At its essence, the sentence reads:

"Each of... indicate..."

Since the sentence starts with "each of", we know that we need the singular verb "indicates".

In the vast majority of GMAT SC questions we can ignore everything after "of" when choosing the best answer.

each (one) of the photographs indicates

Stuart Kovinsky wrote:

lalabee wrote:"He is one of the persons who make money."

however, in the Verbal notes by Sumit:

"To figure out whether the quantifier is singular or plural, we need to check one more thing...
Sometimes, a quantifier refers only to one thing, not many things. For example,
each, every, and one always refer to one thing, but 10%, half, all, and most would refer to more than one thing if the object of the preposition is count (with one possible exception that I will show you in a second).

Of course, if the quantifier is always singular, then the verb must always be singular, too. (Let's not forget our common sense in grammar, okay??) For example, we say:
• One of the people is...
• Each of the students is...

Let's start with "He is one of the persons who make money."

We use the plural "make" in this sentence because "who make money" is part of the description of "people" and not directly related to "he". The singular verb "is" has already been attached to "he".

Looking at the question you posted, we have:

"Scientists say that each of the photographs taken of X by Y indicate... "

As always, we want to ignore the non-essential parts of the sentence when matching up subjects and verbs. At its essence, the sentence reads:

"Each of... indicate..."

Since the sentence starts with "each of", we know that we need the singular verb "indicates".

In the vast majority of GMAT SC questions we can ignore everything after "of" when choosing the best answer.

As Stuart has correctly pointed out that you have to use the singular verb.
but there is another issue in this sentence and that is of parallelism. The extent of flooding should be parallel to the 'degree to which rocks..' hence you can eliminate choice (e) and use (d). Hope this would give one more perspective to be looked at.

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