Which of the following cases would be suitable response variables for a survival analysis?

a. Number of days a patient survives between admission to hospital and death.

b. Age of first mating for a mayfly, measured from the time of adult emergence.

c. Number of deaths per day during an influenza outbreak.

d. Trunk length of surviving elephants after poaching episode.

e. Time to release from hospital after beginning of chemotherapy.

f. Duration of a nap, from falling asleep to waking.