Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : The three stages of prenatal growth are sequential and do not overlap.
Reason (R) : Each stage of prenatal growth is characterized by different physical and cognitive developments and has distinct vulnerabilities to teratogens.
In light of the above statements, choose the most appropriate answer from the options given below.