Let M be a single-tape deterministic TM with tape alphabet { blank, 0, 1 }, and let C denote the
( possibly infinite ) computation of M starting with a blank tape. The input to each problem is M,
together with a positive integer n. Which of the following problems is(are) decidable ?
I. The computation C lasts for at least n steps
II. The computation C lasts for at least n steps, and prints 1 at some point after step
III. M scans at least n distinct tape cells during the company C
(A). III only
(B). I and II only
(C).I and III only
(D).I,II and III