What is the time complexity for the following C module? Assume $n > 0$.\n```c\nint module(int n)\n{ \n if (n == 1) return 1;\n else return (n + module(n - 1));\n}\n```
- A. $O(n)$
- B. $O(\log n)$
- C. $O(n²)$
- D. $O(n!)$
Answer: A. $O(n)$
Explanation: Recursion depth is n. Each call does constant work. $T(n) = T(n-1) + C \Rightarrow O(n)$.