Which One of the Following Does a Variance Do

Which one of the following does a variance do?

A) Alert managers early to events not easily nor immediately evident.
B) Reflect the degree of influence that a specific manager has over costs,revenues or related items for which he or she is responsible
C) Describe the practice of underestimating budgeted revenues,or overestimating budgeted costs,to make budgeted targets more easily achievable
D) All of these answers are correct.