There was only one option: Drop the bombs on Hiroshima and Nagasaki or prepare for a full-fledged invasion of Japan, which would’ve resulted in (at minimum) a million America servicemen dying and an equal number, if not double, that in Japanese civilians. An unimaginable horror with repercussions that would’ve led to the Soviets occupying a good chunk of Japan (which they were badly hoping to do), just for starters, and perpetual bitterness and hatred between our two nations in the aftermath. It would’ve weakened us both and massively empowered the Soviets and the Communist cause.
Back when this country fought wars to win them.
Here's a few alternatives the other side uses, details at link:
Argument 4: There Were Alternatives
Alternative 1: A Demonstration of the bomb
Alternative 2: Wait For the Russians
Alternative 3: Let the Japanese Keep Their Emperor
Alternative 4: Continue Conventional Bombing