d) print(len(t)) is incorrect.
In python, len(t) is a built-in function that returns the number of items in the tuple t. Since t contains 4 items, len(t) would correctly return 4.
a) print(t[3]) is correct, it will return the fourth element of the tuple which is 3.
b) t[3] = 45 is incorrect, tuple is immutable, so you can't assign a value to an element of tuple.
c) print(max(t)) is correct, it will return the maximum element of tuple which is 4.