WASHINGTON (AP) — President Joe Biden’s choice to head the Securities and Exchange Commission has told Congress that the agency should address how to protect investors who use online stock-trading platforms with flashy gimmicks that entice them to trade more. Gary Gensler testified by video Tuesday for his confirmation hearing by the Senate Banking Committee. He was asked about the roiling stock-trading drama involving GameStop shares that has spurred clamor for tighter regulation of Wall Street. Among the issues to be examined, he said, is the use of “behavioral” technology in stock-trading apps. He asked: “What does it mean when you have behavioral prompts to get investors to do more transactions?”