Problem #12 Write a .c function that takes one double parameter, and returns a char. The parameter represents a grade, and the char represents the corresponding letter grade. If you pass in 90, the char returned will be A. If you pass in 58.67, the char returned will be an F etc. Use the grading scheme A(90-100), B(80-89.9), C(70-70.9), D(60-69.9), F( 0-59.9). Ask the user at the end if he/she wants to continue. Use a loop to implement that feature.