Questions: The small squares on the EKG paper equal:

The answer is the first one (a): 1 mm high.

Explanation for each option:

a. 1 mm high: This is correct. On EKG paper, each small square is 1 mm in height and 1 mm in width. This measurement is used to help determine the amplitude of the electrical activity of the heart.

c. .20 sec: This is incorrect. Each small square on EKG paper represents 0.04 seconds, not 0.20 seconds. The larger squares, which are made up of five small squares, represent 0.20 seconds.

d. Both A & B: This is incorrect because option B is not correct. Only option A is correct.

In summary, the small squares on the EKG paper are 1 mm high.