Answer:
I know my behavior is going to affect the group, so I'm trying to be positive
Step-by-step explanation:
The word affect means to have an effect on something or someone.
It is most easily confused with the word 'effect' which means a change happening as a consequence of something.
The first two options would be correct if the word 'affect' is changed to 'effect' because the sentences are talking about a change occurring as a consequence or result of something.
Therefore, the correct answer is C because the narrator knows that his behaviour would have an effect on his group members.