How long after fertilization does the blastocyst implant into the endometrium?

A) 1 day
B) 6-7 days
C) 2-3 days
D) 21 days
E) 13-14 days

Blastocyst

An early stage of embryonic development characterized by a hollow sphere of cells, which implants into the uterine wall as part of pregnancy initiation.

Endometrium

The mucous membrane lining the interior of the uterus, which thickens during the menstrual cycle and is shed if pregnancy does not occur.