Which of the following statements is true? a) both the square root of 0.25 and -the square root of 16 are irrational. b) the square root of 0.25 is rational and -the square root of 16 is irrational c) both the square root of 0.25 and -the square root of 16 are rational d) the square root of 0.25 is irrational and -the square root of 16 is rational