Which of the following would the Supreme Court likely refuse to hear because of "mootness"?

$$ a$)$ a case involving a dispute between the president and the Congress over access to top secret documents

$$ b$)$ a case involving a student suing a state$-$run university for discrimination in the admissions process after the student was first rejected but then later admitted to the university

$$ c$)$ a case involving a citizen suing the Social Security Administration for failure to deliver Social Security benefits prior to the time the citizen was scheduled to receive the benefits

d$)$ a case involving a convicted murderer challenging the constitutionality of the death penalty while on death row