Bhandaripreeti wrote:Whereas the use of synthetic fertilizers has greatly expanded agricultural productivity in many parts of the world, an increase in their use can create serious environmental problems such as water pollution and their substitution for more traditional fertilizers may accelerate soil structure deterioration and soil structure

This is the correct answer.
My question is the subject is - the use of synthetic fertilizers, how can the the pronoun their refer to - the use of fertilizer.

Thanks ,

Regds

I think Bhandaripreeti, you yourself have given the answer, their here cannot refer to "use of synthetic fertilizers", because in the later part of the sentence we have "increase in their use can create serious environmental" .. so here 'their' has to be fertilizers.

Lets wait for the verbal gurus to throw some light..

G'rant,

You need no assistance from verbal gurus! That's exactly right! 'Their' is referring to the fertilizers not to the entire expression 'use of fertilizers'. A pronoun does not have to refer to the subject of the sentence, it only needs to refer to a noun. In this case fertilizers is the object of a preposition and a noun, and so qualifies. Also the entire expression is 'their use', so their has to refer to fertilizers, otherwise this would be in effect saying 'the use of fertilizers use', which doesn't make any sense.

Thanks Danielle, that clarifies.

Regds,
Preeti