Read the sentence.

Carl Sagan himself wrote that document.

What kind of pronoun is himself?

intensive

relative

reflexive

demonstrative

It is a reflexive pronoun because it ends in "self"

intensive

Explanation:

Himself is an intensive pronoun in this sentence because it emphasizes that Carl Sagan wrote that document all by himself. An intensive pronoun usually is found immediately after the noun that it intensifies. An intensive pronoun can also be removed from the sentence and the sentence will be grammatically correct. If we changed the sentence to "Carl Sagan wrote that document all by himself" himself becomes a reflexive pronoun. It cannot be removed or the sentence will not be grammatically correct.