The answer b, is incorrect.
The correct answer is a. I just took the test and used the answer the other user gave because i had a feeling it was wrong. I got a 90 lol.
The correct answer is indignant.
Being indignant means being angry or furious when you feel that something is unjust or outrageous, In this instance, Mrs. Fletcher is furious and outraged (indignant) that Mrs. Pike, who does not even know her (Mrs. Fletcher), knows about her pregnancy. Her indignance is further exemplified when she says, "The nerve of some people!".