What is the effect of 'int mat[3][3] = {0};' in C?

• A. All elements are initialized to zero
• B. Only the first element is zero, rest are indeterminate
• C. It is invalid C code
• D. It creates a 3x3 matrix of ones

Answer: (A)

In C, initializing a multi‑dimensional array with an incomplete initializer fills the unspecified elements with zeros. Here, the 3×3 int array has a single initializer, so the first element mat[0][0] gets 0 and all the remaining elements are zero-initialized as well. The result is a 3×3 matrix where every entry is 0. This is valid C code, and it does not produce ones or indeterminate values.