请选择ABCD(F3h7zPicking apples was hard work, ________ they really enjoyed it.2`8U(W9o4v-X)d8V2f)[4@8Q9^5_
A. and2`8U(W9o4v-X)d8V2f)[4@8Q9^5_
B. so2`8U(W9o4v-X)d8V2f)[4@8Q9^5_
C. but2`8U(W9o4v-X)d8V2f)[4@8Q9^5_
D. or2`8U(W9o4v-X)d8V2f)[4@8Q9^5_