Why did martin luther king travel to memphis tennessee in 1968?

Martin Luther King was political activist, spokesperson and leader in the civil rights movement, who organized “Poor People’s Campaign” in 1968. to address the issue of economic justice in the USA. Due to poor working conditions, two sanitation workers, Echol Cole and Robert Walker, have died in garbage compacts in Memphis Tennessee which was the cause of Memphis Sanitation Strike, alongside the poor salary. Martin Luther King went to support the Memphis Sanitation Strike on March 18th and gave a speech “I’ve Been to the Mountaintop” in front of thousands sanitation workers in front of Clayborn Temple. He had an idea to unite public workers in nonviolent protest and march on the Capitol until Congress creates "economic bill of rights".

the answers is b.   environments.

its c not d   tell me if that´s correct