In this task, you need to count the number of times the given letter appears in the given sentence.

[EX Q]: Sentence: 'two zebras feed on a plant through some wire mesh'. Find frequency of the letter 'o'
[EX A]: 4

[EX Q]: Sentence: 'small black bird with red on its head standing on a tree branch'. Find frequency of the letter 'b'
[EX A]: 3

[EX Q]: Sentence: 'food cooking inside of an electric oven on a baking sheet'. Find frequency of the letter 'a'
[EX A]:
3