Given the task definition, example input & output, solve the new input case.
In this task, you need to count the number of words in a sentence that contain the given letter
Example: Sentence: 'two gray birds standing in a green field'. How many words contain the letter 'a' in the sentence.
Output: 3
The words 'gray', 'standing', and 'a' contain the letter 'a'. So, the answer is 3.

New input case for you: Sentence: 'a group of people with umbrellas are walking across a bridge'. How many words contain the letter 'k' in the sentence.
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
1