Margot Is Pregnant with Her First Child,and She Is Deliriously

Margot is pregnant with her first child,and she is deliriously happy! She and her husband have some tests taken,but before the doctor can come in and review the results,Jim sneaks a peak at the file with the test results.He sees that the baby has "two X chromosomes." He looks at his wife and says

A) Congratulations, honey, we're having a boy!
B) Congratulations, honey, it looks like we are having twins!
C) Congratulations, honey, I need to take a biology class!
D) Congratulations, honey, we're having a girl!