There are N sequences with 15 terms and the following properties:
- each term is an integer,
- at least one term is between -16 and 16, inclusive,
- the 15 terms have at most two different values,
- the sum of every six consecutive terms is positive, and
- the sum of every eleven consecutive terms is negative.
The value of N is
Answer Choices
A. 48
B. 72
C. 64
D. 80
E. 56