Final answer:
A small enterprise may not be able to afford an expensive control system due to limited financial resources, but the reason that a control system loses effectiveness without quantitative standards is not a sufficient explanation for this. Therefore, the correct option is A.
Step-by-step explanation:
Assertion (A): A small enterprise cannot afford to install an expensive control system. Reason (R): Control system loses some of its effectiveness when standards cannot be defined in quantitative terms.
The correct choice is (A) - Both (A) and (R) are true, but (R) is not the correct explanation of (A).
A small enterprise might not be able to afford to install an expensive control system due to limited financial resources. However, the reason that a control system loses effectiveness without quantitative standards is not a sufficient explanation for why a small enterprise cannot afford it.