A student has to opt for 2 subjects out of 5 subjects for a course. Namely commerce, economics, statistics, mathematics 1 and Mathematics 2, Mathematics 2 can be offered only if mathematics 1 has also opted. The number of different combinations of two subjects which can be opted is_________?

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A student has to opt for 2 subjects out of 5 subjects for a course. Namely commerce, economics, statistics, mathematics 1 and Mathematics 2, Mathematics 2 can be offered only if mathematics 1 has also opted. The number of different combinations of two subjects which can be opted is_________?

A. 5
B. 6
C. 7
D. 18

Explanation:
Number of ways of opting a subject other than Mathematics II = 4C2. = 4x3x2!/2!x2 = 6.
Number of ways of selection of Mathematics II = 1
Therefore, Total Number of ways = 6+1 =7.