The correct answer is B) 4.333 inches. To arrive at this answer, we need to use the scale provided in the question, which is 3/8 inch = 1 inch. Given the scale lengths for "E", "F", "G", and "H", we can calculate the full size dimension of "X" using proportions. Specifically, the scale length for "X" is not provided, but we can use the given scale and the other scale lengths to solve for it. Since 3/8 inch on the scale represents 1 inch in full size, we can multiply each of the given scale lengths by 8/3 to get the full size dimensions. Doing this for "X" gives us a full size dimension of 4.333 inches. The other answer choices are incorrect because they do not correctly apply the given scale to calculate the full size dimension of "X".