Which of these is a substance with a strong smell secreted by some animals and used in making perfume?

Musk is a class of aromatic substances commonly used as base notes in perfumery. They include glandular secretions from animals such as the musk deer, numerous plants emitting similar fragrances, and artificial substances with similar odors.

"Musk" was a name originally given to a substance with a strong odor obtained from a gland of the musk deer. The substance has been used as a popular perfume fixative since ancient times and is one of the most expensive animal products in the world.

Natural musk was used extensively in perfumery until the late 19th century when economic and ethical motives led to the adoption of synthetic musk, which is now used almost exclusively. The organic compound primarily responsible for the characteristic odor of musk is muscone.

Modern use of natural musk pods occurs in traditional Chinese medicine.

Musk has been used to attract wild animals, including in man-made perfume mixtures. For example, in 2018 Indian authorities used the perfume Obsession by Calvin Klein to attract and thus trap a wild tiger that had attacked and killed more than a dozen humans.