1) one of the country sends 41 reps.

Which means that 75-41=34 reps for the rest. Now, there is one more criteria, that A should send the second highest number of reps. we should take two cases to prove 1) is may or may not be true. Pick A=9 reps which leaves 25 reps for 4 countries and they can be easily spread with no overlaps(satisfying on other condition). Now, pick A=10 (as it is mentioned atleast)- when A=10, there are 24 reps left that can also be spread across the rest of the 4 countries. Hence, 1) does not answer the question definitively. Hence, choice A and D are ruled out.

2) Country A sends fewer than 12 which means upto 11 reps. Now again pick A=9 and since, A sends the second highest number of reps, one other country sends >9 say 10 reps which leaves, 56 reps to be spread among rest of the 4 countries. Now, pick A as 10 and another country that sends more than A as 11 which leaves, 54 reps to be spread among the 4 countries.

Since, A can send 10 or 9 reps and still satisfy the conditions, we cannot answer the question with statement 2.

Hence, choice B is ruled out.

Combining 1) and 2) gives- one of the country sends 41. Pick A=9 and A=10 and apply the same process as before which satisfies the conditions for both A=9 and A=10- does not give a definitive answer. Hence C is not sufficient.

So, the answer should be E. What is OA?

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To find what you seek in the road of life, the best proverb of all is that which says:

"Leave no stone unturned."

-Edward Bulwer Lytton