A domestic initiative that President Nixon was responsible for was

Correct answer: Creating the Environmental Protection Agency

Explanation/detail:

Based on answer choices I've seen elsewhere, the other options were foreign policy initiatives - - the formal recognition of China and Strategic Arms Limitations Talks (SALT). There was also a decoy answer about reducing interest rates, but that wasn't a successful policy initiative on Nixon's part. During the Nixon presidency, the Federal Reserve chairman, Arthur Burns, had begun raising interest rates. In 1971, President Nixon exerted pressure on Burns and "the Fed" to keep interest rates down, but that only led to a decade of high inflation that caused other economic problems. So that was not a success for Nixon.

About the Environmental Protection Agency

President Nixon signed an executive order establishing the Environmental Protection Agency in 1970. Subsequent committee hearings in the House of Representatives and the Senate ratified Nixon's order for the creation of the agency.

Environmental issues had been gaining much attention during the 1960s, and the need for oversight became clear. As Lily Rothman reported in a TIME magazine article:

An oil spill off the California coast in 1969 coated 400 square miles with slime and killed hundreds of birds. Scientists announced that auto exhaust was at high enough levels in some places that it could cause birth defects. The city of St. Louis smelled, as one resident put it, "like an old-fashioned drugstore on fire."

- "Here's Why the Environmental Protection Agency Was Created," TIME, March 22, 2017

Nixon's administration felt it necessary to take action to address pollution problems in the American environment.