So I'm assuming this is a pythagorean theorem problem, and it involves right triangles. If this is the case, then we can use the formula: a² + b² = c². In this case, it gives us the values of a and b, so we have 3² + 4² = c². This is equal to 9 + 16 = c², and further simplified, 25 = c². So we can then find the square root of 25, written as √25, which would equal 5, as 5² = 5 * 5, and 5 * 5 = 25. So therefore your answer would be A. 5 feet. Hope this helps! :D. Feel free to ask questions about my explanation and ask more questions.