Answer:
i'm assuming the answer is "were / had painted."
Step-by-step explanation:
none of the other answers appear to be grammatically correct.
A. "we was very tired because we were painting the house."
B. "we was very tired because we had painted the house."
C. "we had been very tired because we painted the house."
D. "we were very tired because we had painted the house."
from what i can see, only D fits as an answer, however, the format is a little confusing to me. apologies if this is incorrect!