Looking at the options you could easily eleminate B, D, C.
If you read carefully " Investments inservice, like those in production and distribution, must be balanced against other types ofinvestments on the basis of direct,tangible benefits such as cost reduction and increased revenues". It says that the investment must be balanced against the tangibility etc in terms of what will be overall gain. If we pick up A, tangibility of the benefits that they tend to confer, it will narrow down the scope of the answer. However in C, it keeps the broad scope of the argument.