why pm reluctant to delegate work?

hi friends,

what should be the answer which is NOT the excuse pm commonly use for not willing to delegate work?

a. "my subordinates aren't sufficiently qualified."

b. "subjects are too confidential to involve others"

c. "my subordinates are not interested in additional responsibilities"

d. "i can do it better"

Please tell me why you choose / not choose the answer.

regards

Moranz