A1
used instead of "a" when the following word begins with a vowel sound
Dictionary examples:
An elephant ate an entire ice cream! (0.0)
An octopus wore an orange hat. (0.0)
An apple a day keeps an elephant away. (0.0)
an orange (11.0)
an interesting story (12.5)
an easy question (15.3)
an honest person (19.7)