Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In cockroaches, the presence of anal styles serves as a feature of external sexual dimorphism, whereas anal cerci do not. Reason (R): Anal styles are unjointed structures found only on the 9^ th segment of males, whereas anal cerci are jointed structures present on the 10^ th segment of both sexes.

Step-by-step solution

Assertion (A) is true because anal styles are a distinguishing feature present only in male cockroaches, making them a reliable marker for external sexual dimorphism. Anal cerci are present in both males and females, so they do not help in distinguishing the sexes externally. Reason (R) is true and provides the correct anatomical explanation for the assertion. Anal styles are found only on the 9^ th segment of males, whereas anal cerci are found on the 10^ th segment of both sexes. Thus, Reason correctly explains t