The situation wherein you have to drop the final e in a base word before adding a suffix is when the suffix begins with a vowel. The answer is option D. Vowel suffixes include: -ance, -er, -ing, -able, -est, -ed, ation. For example, the word, MAKE. Make ends ine. But when connected to a vowel suffix, the letter e is dropped and becomes = MAKER OR MAKING.
