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

[Q]: Sentence: 'a bathroom with a sink, counter top, and mirror is shown'. Find frequency of the letter 'i'
[A]: 4


[Q]: Sentence: 'two zebras standing around while a third zebra drinks from a pond'. Find frequency of the letter 's'
[A]: 3


[Q]: Sentence: 'a large commercial airplane parked on a runway'. Find frequency of the letter 'o'
[A]:
2