How is the indefinite singular indicated for adjectives?

Adjectives in the indefinite singular:

Click the selected answer; there are several correct answers.

1.   Have no ending if the noun is an n-word.
2.   Have the ending –e when the noun is an n-word
3.   Have the ending –t when the noun is a t-word
4.   Have the ending –e when the noun is a t-word.