The correct answer is option 1 - Parotid gland. Mumps is a viral disease caused by the mumps virus. It primarily affects the parotid glands, which are the largest salivary glands located on the sides of the face, just below and in front of the ears.

Option 2 - Sublingual gland, is incorrect because the sublingual gland is a different salivary gland located under the tongue, and is not directly affected by mumps.

Option 3 - Submaxillary gland, is also incorrect because the submaxillary gland, also known as the submandibular gland, is another salivary gland located below the jaw and is not directly associated with mumps.

Option 4 - Infra-orbital gland, is incorrect as well, as there is no gland by the name of infra-orbital gland.