Gland is the correct answer because it is the only term in the given options that is directly related to the other terms. Lungs, loins, and hormone are all related to glands in some way. Lungs are a type of gland that help in the process of respiration, loins contain glands that produce hormones, and hormone is a substance secreted by glands that regulate various bodily functions. Therefore, gland is the most appropriate answer in this context.