Consider the following 100 sets of 10 elements each:

\{1,2,3, \cdots, 10\}

\{11,12,13, \cdots, 20\}

\{21,22,23, \cdots, 30\}

\vdots

\{991,992,993, \cdots, 1000\}

How many of these sets contain exactly two multiples of 7 ?

**Answer Choices**

A. 40

B. 42

C. 42

D. 49

E. 50