A 14-year-old boy was found dead in an apparent suicide Saturday in The Bronx, hours after he and his mother had a heated argument about his poor grades, police sources said.

Cops responded to a 911 call made from Angel Rivera’s parents’ apartment on Jackson Avenue and East 143rd Street in Mott Haven at around 10:10 a.m., and found the teen unresponsive, according to police.

The boy likely swallowed a lethal dose of prescription medication — possibly sleeping pills, a police source speculated. He was rushed to Lincoln Hospital, where he was declared dead.

The night before, he and his mother clashed about his schoolwork, the sources said.

Neighbors remember Rivera as a “lively kid” who loved rock music and never caused trouble.

“He always held the door for me when I was leaving,” a neighbor said. “He would play basketball across the street all the time or hang out with his girlfriend.”

The medical examiner will determine the precise cause of death.