In the given question, a statement of Assertion is followed by a statement of Reason. Mark the correct answer.

Assertion: Al-Biruni attempted to suggest that social divisions were unique to India.
Reason: He pointed out that within Islam all men were considered equal, differing only in their observance of piety.

The Assertion is incorrect but the Reason is correct.

The correct option is: Option 3: The Assertion is incorrect but the Reason is correct.

Assertion: Al-Biruni attempted to suggest that social divisions were unique to India. This statement is incorrect. Infact he suggested that  social divisions were not unique to India. 
Reason: He pointed out that within Islam all men were considered equal, differing only in their observance of piety. This statement is correct.

"Al-Biruni tried to explain the caste system by looking for parallels in other societies. He noted that in ancient Persia, four social categories were recognized: knights and princes; monks, fire-priests and lawyers; physicians, astronomers, and other scientists; and finally, peasants and artisans. In other words, he attempted to suggest that social divisions were not unique to India. At the same time, he pointed out that within Islam all men were considered equal, differing only in their observance of piety."