Toni has . . . . . . . . terrible Stomach ache.

Solution (By Examveda Team)

Toni has an terrible stomach ache.

"An" is used before "terrible" because it starts with a vowel sound. The indefinite article "an" is used before words that begin with vowel sounds to facilitate smoother pronunciation.

Option A: a is incorrect because "a" is used before words that start with consonant sounds. Since "terrible" starts with a vowel sound, "an" is the correct choice.

Option C: the is incorrect because "the" is used for specific references. In this case, Toni's stomach ache is general and not previously mentioned, so the indefinite article is appropriate.

Option D: no article is incorrect because a noun phrase like "stomach ache" needs an article to indicate it is a singular countable noun in this context.

Conclusion: The correct answer is Option B: an, as it correctly follows the rule of using "an" before words that begin with vowel sounds.