A matrix uses a 'union' rule: the third column contains all elements present in either the first or second column. Row 3 col 1 has {diamond, star} and col 2 has {star, cross}. What should col 3 contain?
-
A
{star}
-
B
{diamond, cross}
-
C
{diamond, star, cross}
-
D
{diamond, star, cross, circle}