Which of the following is NOT a simple sentence?

A.In 1968, King was planning a national protest or rally of Washington, D.C. When he was killed on April 4 in Memphis, Tennessee.

B.On October 14, 1964, King won the Nobel Peace Prize for fighting racial
inequality through nonviolent resistance.

C.His death was followed by riots in many U.S. cities.

D.Hundreds of streets in the U.S. have been renamed in his honor.