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

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

[Q]: Sentence: 'a group of tennis players on a tennis court'. Find frequency of the letter 'o'
[A]: 4

[Q]: Sentence: 'a couple of street signs sit on a train light'. Find frequency of the letter 'h'
[A]:
1