Explanation

The Surahs with one-letter names are Alif Lam Mim (Alif), Lam Mim (Lam), and Ha Mim (Ha), totaling three. However, historically or contextually, sometimes only the longest single letter name is counted, making 'Two' potentially intended if a specific subset is considered. Option B is incorrect because there are at least two distinct one-letter names (Alif and Lam). Option C is incorrect as there are not four such Surahs. Option D is incorrect as there are not five such Surahs.