Revenue expenditures:

Revenue expenditure refers to those expenditures which are incurred during normal business operation by the company, benefit of which will be received in the same period and the example of which includes rent expenses, utility expenses, salary expenses, insurance expenses, commission expenses, manufacturing expenses, legal expenses, postage and printing expenses, etc.

it is a. 4.2 because 7.6-3.4 gets the remaining length of 4.2. i might be wrong but i am pretty sure this is the answer.