Answer:
C. -25
Explanation:
Since the current number is -55, it depicts the number to achieve the target.
That is the current position states that we require 55 more units to produce.
If we produce 30 more units in an hour, we shall require 55 - 30 = 25 more units to produce, in order to achieve target.
Since target is decreased by 30, but yet not achieved completely it will still be a negative number.
Thus, the correct answer is
C. -25
This depicts that achieved volume of units is short by 25 units in order to achieve the target.