The correct answer is option 'C': Both 1 and 2.

Explanation:
Mumps is a contagious disease caused by the mumps virus. It primarily affects the salivary glands, leading to swelling and pain in the jaw area. However, the virus can also cause inflammation in other parts of the body, such as the testicles, ovaries, and brain.

Let's analyze the given statements in detail:

1. It is a contagious disease caused by the virus.
This statement is correct. Mumps is indeed a contagious disease caused by the mumps virus. The virus is primarily spread through respiratory droplets, which are expelled when an infected person coughs, sneezes, or talks. It can also spread through close contact with an infected person, such as sharing utensils or kissing. The virus can survive on surfaces for a short period, allowing for indirect transmission.

2. Humans are the only known host for mumps virus.
This statement is also correct. Humans are the only known host for the mumps virus, meaning that the virus can only infect and replicate within human cells. Unlike some other viruses, such as influenza or rabies, mumps does not have a significant animal reservoir. This makes humans the primary source of transmission and the target population for vaccination efforts.

Mumps is generally a self-limiting disease, with symptoms including fever, headache, muscle aches, fatigue, and the characteristic swelling of the salivary glands. However, complications can occur, particularly in older individuals or those with weakened immune systems. These complications can include orchitis (inflammation of the testicles), oophoritis (inflammation of the ovaries), meningitis (inflammation of the membranes surrounding the brain and spinal cord), and pancreatitis (inflammation of the pancreas).

To prevent the spread of mumps, vaccination is crucial. The MMR (measles, mumps, and rubella) vaccine provides effective protection against mumps. It is recommended for all children and adults who have not been previously vaccinated or had the disease. Vaccination not only protects individuals from mumps but also helps in achieving herd immunity, reducing the overall transmission of the virus within the population.

In summary, mumps is a contagious disease caused by the mumps virus, and humans are the only known host for this virus. Vaccination plays a crucial role in preventing the spread of mumps and its associated complications.