consider the sets.

Question

A= {distinct letters in work Keep}
B= {13}
C= {k,e,p}
D= 1 in red + 1 in black}
E= {two}
F= {2}
What is the cardinality of each set?
A= I can not figure that one out
B= 1
C= 3
D= 0
E= t,w,o
F not sure
Can you give me some ideas
Thank you