Could anyone please resolve this query ?

D implies 'period' lasted longer than half million years. That is incorrect. The 'human beings' lasted longer than half million years.

garson0in wrote:Q14 -
Almost the only evidence of the presence of human beings on the earth for a period longer than half a million years are vast quantities of stone tools.

a)longer than half a million years are
b)of more than half a million years are
c) of more than half a million years is
d) lasting longer than half a million years is
e) of longer than half a million years are

I understand that the verb are is incorrect. Therefore the options are reduced to C and D. The OA is C. Both seem correct to me. How do we arrive at the conclusion ?

'period of more than' doesn't make any sense. 'period more than' or 'period longer than' makes sense.

The only choice that makes sense to me is [A]. Is that correct? What is OA and explanation please?

I think we have to go with logical interpretation here. Period of human being existed is still continue in the present .

My doubt is not cleared yet. Could anyone else help ?

'vast quantities of stone tools' this is should attract a plural verb. Thus, all option that has 'is' as the preceding verb are automatically invalid.
Option A.
' a period of' this would have been a better synchronism with the sentence. Thus this option is wrong.

Option B.
This is the correct answer.This option perfectly satisfies the proper usage of tenses and grammar, the use of 'a million years' is instrumental to why this option is given a nod.

Option C.
'is' this is the only difference between option B and option C. Mind you the question was talking about 'vast quantities of tool stones' so it must attract a plural verb.

Option D.
wrong English construction that is even visible to a blind man. Thus this option is incorrect.

Option E.
'of longer than' that is an awkward construction. It should have been better re-structured.