Which of the following statement describes dinosaurs during the mesozoic era?
a. they were very inactive
c. they were good mothers
b. they were cold-blooded
d. they are the direct ancestors to birds today

Option (D)

Explanation:

The dinosaurs of Mesozoic era are directly related to the present day birds. The birds are evolved from the theropod dinosaurs. The oldest birds were originated about 150 million years back and has undergone evolution, where their teeth were replaced by the beaks. From the evidences, it has been found that the birds and the extinct dangerous dinosaurs named "T. Rex" has the same ancestors, and they were the Coelurosauria dinosaurs. The birds are often considered as the living dinosaurs.

Thus, the Mesozoic dinosaurs are the direct ancestor of the present day birds.

Hence, the correct answer is option (D).

d. the weight of the book