He is a better politician than . . . . . . . . orator.

The correct answer is D. no article.

The word "orator" is a noun that refers to someone who is skilled in public speaking. It is a common noun, which means that it does not have a specific reference. In this case, the speaker is comparing the politician to orators in general, so there is no need for an article.

If the speaker were comparing the politician to a specific orator, such as Winston Churchill or Martin Luther King, Jr., then an article would be necessary. For example, the speaker could say "He is a better politician than Winston Churchill."

In addition, if the speaker were referring to a type of orator, such as a political orator or a religious orator, then an article would also be necessary. For example, the speaker could say "He is a better politician than a political orator."

However, in the given sentence, the speaker is simply comparing the politician to orators in general, so there is no need for an article.