Look for the largest square factor of 52. Since 52 = 4 × 13 and √4 = 2, we get √52 = 2√13. To simplify a surd, split the number under the root into a perfect-square factor and the remaining factor. Take the square root of the perfect square outside the radical. The expression is simplified when no square factor greater than 1 remains under the root. The correct answer is 2√13, which matches the calculation or reasoning shown.