Sentence Correction

//the rising of costs// of data processing operations at many financial institutions has created a growing opportunities for independent companies to provide these services more efficiently and at lower cost

a,

b, rising costs

c, the rising cost

d,because the rising cost

e,because of rising costs.

Og said that it is unidiomatic to use A and C is idiomatic. I do not understand this. pls,help

Its a SUbject VErb issue.

The rising costs ............... has ---> Incorrect
The rising cost ------------- has ----> Correct

Hence "C".

Shawshank...

why A is wrong

This question is already posted. I am unable to get the link.

However, to answer, costs in plural.