Which of the Following Statements Is False

Which of the following statements is false?

A) The <= operator tests whether the set to its left is an improper subset of the one to its right-that is, all the elements in the left operand are in the right operand, and the sets might be equal.
B) You also can check for an improper subset with the set method issubset.
C) You can check for an improper superset with the set method issuperset.
D) The argument to issubset or issuperset must be a set.