Question: To clean rust stains off of the bath tub.

  Options: 
 A. Use half a grapefruit and pepper. Sprinkle about a 1/4 cup of kosher pepper on a halved grapefruit.
 B. Use half a grapefruit and salt. Sprinkle about a 1/4 cup of kosher salt on a halved grapefruit.
Answer: B