In the sentence: “By 1979, Lovelock had put forward his theories on the environment, in his first book.” The word “his” is used twice. In both case...

In the sentence: “By 1979, Lovelock had put forward his theories on the environment, in his first book.” The word “his” is used twice. In both cases it refers to:

a. ( ) 1979.
b. ( ) book.
c. ( ) theories.
d. ( X ) Lovelock.
e. ( ) the environment.