Question

the baby ___ quiety in his crib.
a. was laying
b. was lying
c. laid
d. lain

Answer 1

The baby was lying quietly in his crib.
So the answer is B. Was lying

Answer 2

The baby ___ quiety in his crib.a. was laying
b. was lying
c. laid
d. lain

This is going to be a "paste tense" sentence.
Your answer is was lying.