past paper question on Overhead absorption.

The following question is taken from the January to June 2015 exam period. A company uses a blanket overhead absorption rate of $5 per direct labour hour. Actual overhead expenditure in a period was as budgeted. The under/over absorbed overhead account for the period have the following entries: DR CR $ $ Production overhead 4,000 Profit or loss account 4,000 Which of the following statements is true? A) Actual direct labour hours were 800 less than budgeted B) Actual direct labour hours were 800 more than budgeted C) Actual direct labour hours were 4,000 less than budgeted D) Production overhead was over absorbed by $4,000 Hello The answer to the above question is choice A. I understand how the 800 hours are calculated by taking 4000/5. However I don't understand the concept as to how less hours leads to under absorption. Isn't under absorption occurred when actual overheads and higher that absorbed? so how is there a link to how less hours leads to under absorption. in need of your help. kind regards Sukaina