The correct answer is 16!
Explanation: A morula is distinct from a blastocystin that a morula (3–4 days post fertilization) is a 16-cell mass in a spherical shape whereas a blastocyst (4–5 days post fertilization) has a cavity inside the zona pellucida along with an inner cell mass.A morula, if untouched and allowed to remain implanted, will eventually develop into a blastocyst.