Anatomy Development period- week 1,2,3,4 b8bbd9e5 Hea beat in conceptus can be detected earliest by A 4-6 weeks B 12-14 weeks C 14-16 weeks D 21-24 weeks High-Yield Explanation The CVS is the earliest system to become functional is human. Hea begins to beat in the fouh week of development( Day 22 ).