During the first month or so after conception, ________.

A) the genetic sex of the fetus can be determined using an ultrasound machine
B) the fetus has a structure that will become either a penis or a clitoris
C) the genetic sex of the fetus has not yet been determined
D) the genetic sex of the fetus has not yet been determined, and the fetus has a structure that will become either a penis or a clitoris

During the first month or so after conception, the fetus develops a structure known as the genital tubercle, which will eventually differentiate into either a penis or a clitoris depending on the presence of certain hormones. This occurs well before the genetic sex can be visually determined using ultrasound technology. The genetic sex of the fetus is determined at conception by the combination of sex chromosomes from the sperm and egg.