Which of the following statements about the master method are true?

a. A standard recurrence with a = 1 always falls into case 2 of the master method.

b. A standard recurrence with a = 1 never falls into case 3 of the master method.

c. A standard recurrence with a > b never falls into case 2 of the master method.

d. A standard recurrence with a > b always falls into case 3 of the master method.