24. Let M0 , M1, M2 , . . . , be an effective enumeration of all Turing machines. Which of the following problems
is (are) decidable?
I. Given a natural number n, does Mn starting with an empty tape halt in fewer than n steps?
II. Given a natural number n, does Mn starting with an empty tape halt in exactly n steps?
III. Given a natural number n, does Mn starting with an empty tape halt after at least n steps?
(A) I only (B) II only (C) III only (D) I and II (E) I and III
