The correct answer is B) to within 1% to 3% of its capacity. This is the correct answer because it is the industry standard practice to prevent cargo tank overflow due to expansion. Filling the tank to within 1% to 3% of its capacity allows room for the cargo to expand without spilling over the top. The other options are incorrect because: A) Filling to within 1 to 3 inches of capacity does not provide enough room for expansion. C) Filling to the bottom of the expansion trunk does not leave enough room for expansion. D) Filling 1 to 3 inches from the top of the vent pipe does not directly address the issue of preventing overflow due to expansion.