To spell the word believable, why is the final e dropped from the base word believe?

because the base word ends in consonant + vowel + consonant
because the suffix begins with a consonant
because the suffix begins with a vowel
because this is an exception to the final e rule

The final e is dropped from the base word when we spell the word believable because the suffix begins with a vowel. The suffix used in the word believable is -able. This is one of the vowel suffixes. The general rule is, in order to add a vowel suffix to a word ending in silent e, the final e should be removed then connect the vowel suffix.

How i posted to know cuz