Choose the best answer A, B, C or D

77. The police are asking the man _______ car has been stolen.
A. whom B. whose C. which D. that
78. Spring is the time _______ many kinds of flowers blossom.
A. who B. where C. which D. when
79. Hoa and her dog______________ are standing over there go to the park.
A. that B. who C. whom D. which
80. Do you know the boy ________ won the first prize in the contest.
A. who B. whose C. which D. who