A classmate claims that the number 100 has three significant figures. Are they correct and why or why not?

A. Yes, the classmate is correct because you always count zeros after a non-zero digit.
B. No, the classmate is not correct because you never count zeros after a non-zero digit.
C. Yes, the classmate is correct because you count the number of digits in the number.
D. No, the classmate is not correct because you don't count the trailing zeros if there isn't a decimal.