The correct answer is D) reduced slime and mold. Proper air circulation in an air-conditioned cargo space helps maintain a dry environment, which reduces the likelihood of slime and mold growth. Stagnant air can lead to increased moisture content, creating an environment conducive to the formation of slime and mold. By ensuring adequate air circulation, the cargo space remains drier, preventing the growth of these organisms that can damage cargo. The other options are incorrect because they do not directly address the benefit of reduced slime and mold growth. Increased temperature differential (A) or air density (C) may affect the cargo, but do not specifically address the maintenance of air circulation. Increased moisture content (B) would actually contribute to the growth of slime and mold, which is the opposite of the desired outcome.