Which is a fused sentence? josie will lead the discussion it is about a topic she knows well. ted has not finished reading the assignment because he has been sick. lara will ask the group questions that she has prepared in advance. kyle will listen to group members and take notes on what they say.

Only one of these sentences stands out quite obviously as grammatically incorrect. 

B, C, and D are all correct. Why? I'll bold the reason in each:

B: Ted has not finished reading the assignment because he has been sick.
C: Lara will ask the group questions that she has prepared in advance.
D: Kyle will listen to group members and take notes on what they say.

The words I bolded are all words that help each sentence flow smoothly. Each of these are correct. 
However, this leaves us with A.

A: Josie will lead the discussion it is about a topic she knows well. 
This is grammatically incorrect. This sentence SHOULD have been written in three different ways:
1. Josie will lead the discussion. It is about a topic she knows well.
2. Josie will lead the discussion, it is about a topic she knows well.
3. Josie will lead the discussion; it is about a topic she knows well. 

But because this sentence lacked the proper use of punctuation or transition words, it is incorrect.
Your answer is A.

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Aand c is your answer btw your welcome