Which of the following is a dependent clause?
a.
while we were eating dinner.
b.
after the disruption, we left.
c.
we saw a group of people laughing.
d.
people wearing tinfoil hats crowded the street.

I think the correct answer from the choices listed above is option A. The clause which states that "While we were eating dinner." is a dependent clause. The reason is that it still needs some other sentence in order to complete the thought or complete it wants to mean.