This is an example of D. irony. Irony is when you say something which is actually the opposite of what you think, in order to make a funny statement. So, this person said the doctor was unusually prompt (which means punctual, someone who always arrives on time), even though he was half an hour late. <span />
Sleep deprivation can be detrimental, as it can cause damage to the brain. The damages that the brain can face are being unable to learn or adapt to new things and very important neurons being killed.
