Combinatorics [closed]

Question

I think the correct answer must be (C). Please let me know what's correct.

Inclusion-exclusion principle is used.

Comments

i asked this question a few days back. Correct answer is C only.

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Although inclusion exclusion works here, an easier DP solution can be used for this problem which will generalise to more than 2 dotted lines too.

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http://mathforum.org/library/drmath/view/66728.html by using this we can get C option