Which Statement Is Correct

Multiple Choice

Which statement is correct?

A) Implantation is accomplished by enzymatic activity of the trophoblastic layer of the ovum.
B) The endometrium at the site of implantation is converted into the nutrient-rich decidua.
C) Implantation occurs within 24 hours after fertilization.
D) Implantation is accomplished by enzymatic activity of the trophoblastic layer of the ovum, and the endometrium at the site of implantation is converted into the nutrient-rich decidua.
E) All of these.