What is the shape of the following distribution?
{9, 10, 10, 11, 11, 12, 12, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 19, 20]

A.negative skew
B.postive skew
C.symmetric
D.asymmetric with no skew
E.none of the above