Which muscle is known for its role in smiling and elevating the corners of the mouth?

The zygomaticus muscle is primarily responsible for smiling and elevating the corners of the mouth. This muscle has two parts, the zygomaticus major and the zygomaticus minor, which originate from the zygomatic bone and insert into the skin at the corners of the mouth. When the zygomaticus contracts, it pulls the mouth's corners upward, creating a smile.

In contrast, the masseter muscle is mainly involved in chewing and jaw movement, while the orbicularis oris encircles the mouth and is responsible for actions like puckering the lips. The depressor anguli oris, as the name suggests, pulls the corners of the mouth downwards, which is the opposite of a smiling action. Thus, the zygomaticus muscle's specific function in facilitating upward movement at the corners of the mouth makes it the correct choice for this question.