Which star of "What's Happening!!" passed away at age 60 due to cancer?

The correct answer is Danielle Spencer. She was a prominent star on the sitcom "What's Happening!!," where she played the character Dee Thomas. Her passing at the age of 60 due to cancer is a notable event that garnered attention and reminded fans of her contributions to television.

While Redd Foxx, Marla Gibbs, and Shirley Hemphill are also significant figures associated with classic television and have had successful careers, they did not pass away at age 60 due to cancer. Redd Foxx, known for his role in "Sanford and Son," has a celebrated legacy, and Marla Gibbs gained fame from "The Jeffersons." Shirley Hemphill, remembered for her role as Shirley Wilson in "What's Happening!!," also had a lasting impact on television. However, the unfortunate passing of Danielle Spencer is what makes her the correct response in this particular question.