A Patient at 16 Weeks' Gestation Has a Hematocrit of 35

A patient at 16 weeks' gestation has a hematocrit of 35%. Her prepregnancy hematocrit was 40%. Which statement by the nurse best explains this change?

A) "Because of your pregnancy, you're not making enough red blood cells."
B) "Because your blood volume has increased, your hematocrit count is lower."
C) "This change could indicate a serious problem that might harm your baby."
D) "You're not eating enough iron-rich foods like meat."