since C+12 = 2R, R = (c + 12)/2
R has to be an integer, so let's take the greatest possible tapes C could have given condition (B),
Plugging in 11 for C, is ruled out since R = 23/2 (not an integer)
Plugging in 10 for C, R = 11;
So the greatest possibililty of C is lesser than what it would result for R. So (B) is sufficient.
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