To find the total surface area of the sawhorse, we need to calculate the areas of all the six faces and then add them up.
The sawhorse has 2 faces that are 36 inches tall and 30 inches long, so the area of each of these faces is 36 * 30 = 1080 square inches. There are 2 such faces, so total area = 2 * 1080 = 2160 square inches.
The sawhorse also has 2 faces that are 36 inches tall and 24 inches wide, so the area of each of these faces is 36 * 24 = 864 square inches. There are 2 such faces, so total area = 2 * 864 = 1728 square inches.
Finally, the sawhorse has 2 faces that are 30 inches long and 24 inches wide, so the area of each of these faces is 30 * 24 = 720 square inches. There are 2 such faces, so total area = 2 * 720 = 1440 square inches.
Adding up all these areas, we get:
2160 + 1728 + 1440 = 5328 square inches
Therefore, the total surface area of Jen's sawhorse is 5328 square inches. So the closest answer choice is 3,861 square inches.