To solve this question, the user needs to identify the seventh vowel in the given sentence and determine whether it is the letter "a" or not.

The given sentence is "The seventh vowel appearing in this sentence is the letter 'a'."

The vowels in the sentence are: e, e, e, a, i, i, a, i, e, e, i, a, e, e.

Counting from left to right, the seventh vowel in the sentence is the letter "i" and not "a". Therefore, the correct answer is:

The Answer is: B. False