Final answer:
The word 'challenge' can be used as a noun or a verb with different meanings.
Step-by-step explanation:
In excerpt A, the word 'challenges' is used as a noun and refers to difficult tasks or problems that need to be overcome. For example, in the sentence 'John faced many challenges in his new job,' challenges is used to describe the difficult tasks John had to face.
In excerpt B, the word 'challenge' is used as a verb and means to work together on a difficult task or problem. For instance, in the sentence 'The team will challenge the reigning champions,' challenge is used to indicate that the team will compete against the champions.
Therefore, both forms of the word challenge have different parts of speech and meanings. Challenges is a noun, while challenge is a verb.
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