Final answer:
The Pharisees sent the Priests and Levites to question John the Baptist, as they were a religious sect with significant influence in Jewish society.
Step-by-step explanation:
The individuals who sent the Priests and Levites to question John were the Pharisees. This religious group, known for strictly adhering to the laws of Moses and expecting all Jews to do the same, was very active in the Jewish community. The Pharisees, along with the Sadducees, constituted the major religious sects that had significant influence over the religious and social life of the Jews in the first century CE. It was common during that time for established religious authorities to interrogate new preachers like John the Baptist to ascertain their teachings and intentions.