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

Sentence: 'a person is holding a chocolate doughnut with rainbow sprinkles'. Find frequency of the letter 's'
4

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

Sentence: 'two men practicing surfing in a small water enclosure'. Find frequency of the letter 'e'

4