Mathematics
OpenStudy (anonymous):

The mathematical statement 4 C A means: A) 4 is a subset of A B) 4 is an element of A C) 4 is the intersection of A D) all of the above

OpenStudy (anonymous):

$4\subset A$Means that 4 is a subset of A.

OpenStudy (anonymous):

$4\in A$Means that 4 is an element of A. And about the intersection, it can't be represented in OpenStudy's equation editor but it would look like {4} n A. (Your answer is A)