The correct answer is (a). The small intestine is about 7.5 to 8.5 meters long in adults. It is a long, coiled tube that is located in the upper abdomen. The small intestine is responsible for absorbing nutrients from food. It does this by secreting digestive enzymes and bile, which break down food into smaller molecules that can be absorbed by the body. The small intestine also has a large surface area, which helps to increase the absorption of nutrients.
Option (b) is incorrect because the small intestine is actually shorter than 6.0 to 7.0 meters. Option (c) is incorrect because the small intestine is actually longer than 1.5 meters. Option (d) is incorrect because the small intestine is actually longer than 3.5 meters.