Question 6 Not yet answered Marked out of 1.00 P Flag question Which of the following is not a valid variable name? a. Rate_value O b. Rate O c. Rate 10 O d. $rate Question 5 Not yet answered Marked out of 1.00 Flag question Which format specifier is used if a variable named grade is declared as data type of character? O a. %s V O b. %lf O c. %d O d. %C