The measurement was important and they had to make a, what kind of increase, to get it just right?\nOptions:\n- mighty\n- slight\n- negligible\n- useless\n- petty
Let's think step by step below.
slight
Slight is small in degree and inconsiderable.

The measurement was important, and they had to make a slight increase to get it just right.

.

Thus, the answer is slight