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

[Q]: Sentence: 'a red fire hydrant opened and spilling water'. Find frequency of the letter 'd'
[A]: 4


[Q]: Sentence: 'children with scissors and construction paper in a school classroom'. Find frequency of the letter 'c'
[A]: 6


[Q]: Sentence: 'a group of birds in the sand by the water'. Find frequency of the letter 't'
[A]:
3