In this task, you need to count the occurrences of the given word in the given sentence.

Sentence: 'a pizza is on a cooling rack on a counter'. Count the occurrences of the word 'on' in the given sentence.
2

Sentence: 'a horse and a dog facing each other in a brown field of grass'. Count the occurrences of the word 'a' in the given sentence.
3

Sentence: 'a group of people riding on a boat in a small docking canal'. Count the occurrences of the word 'a' in the given sentence.
3