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.