Without a functional SRY gene on the Y chromosome, a developing embryo will become:

1. Early in development, gonadal tissue is bipotential, meaning it can become either testes or ovaries. 2. A single gene on the Y chromosome, called SRY, is what triggers development toward the male pathway. 3. Since females lack a Y chromosome, they lack this gene entirely. 4. 'Male' is ruled out because becoming male specifically requires the SRY gene's cascade, which is absent here. 5. 'Neither sex (sterile)' and 'both sexes simultaneously' do not match normal human development, which always resolves to one sex. 6. Without a functional SRY gene, an individual will be female by default, confirming females as the 'fundamental' sex in this developmental sense. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 27 "The Reproductive System", p.1309 §Development of the Sexual Organs in the Embryo and Fetus_