UPSC CSE Prelims 2023
The problem requires determining the number of selections of 10 consecutive items from 12 items arranged in a circle, with the selection proceeding in a clockwise direction.
When selecting 'r' consecutive elements from 'n' elements arranged in a circle, and a specific direction (such as clockwise) is stipulated, the number of distinct selections is 'n'. This is because each of the 'n' elements can serve as a unique starting point for a consecutive sequence of 'r' elements in the specified direction. Since n=12 and r=10, the number of such selections is 12.
Options A (3), B (11), and D (66) are incorrect because they do not align with the combinatorial principle applicable to selecting consecutive items in a circular arrangement with a defined direction.