Which of the following statements is TRUE regarding human odor receptors?

The statement that humans have receptors that can sense about a million different substances is accurate. This highlights the complexity and sensitivity of the human olfactory system. The human nose contains approximately 400 types of odor receptors, each of which can detect various specific molecules. Through combinations of these receptors being activated, humans can recognize and differentiate an extensive array of smells, leading to the ability to detect millions of different odorant molecules.

The other statements are not correct as they misrepresent the features of the olfactory system or the nature of odor substances. Having only one type of receptor for smell does not reflect the diversity of scent detection. Furthermore, all odor substances do not share the same molecular shape; they can have varied shapes that lead to different smells being perceived. Lastly, while females may have heightened sensitivity to certain pheromones, both males and females have the biological capacity to detect them.