The wettest place in India is generally considered to be Mawsynram, which is located in the state of Meghalaya. Mawsynram receives extremely high amounts of rainfall throughout the year, with an average annual rainfall of around 11,871 millimeters (467.4 inches). This makes it one of the wettest places on Earth.

Mahabaleshwar, located in the state of Maharashtra, is known for its pleasant climate and receives high rainfall during the monsoon season. However, its average annual rainfall is significantly lower than that of Mawsynram.

Cherrapunji, also located in Meghalaya, used to hold the title of the wettest place on Earth. It still receives heavy rainfall, but Mawsynram has surpassed its average annual rainfall in recent years.

Udhagamandalam, also known as Ooty, is a hill station located in Tamil Nadu. While it receives a decent amount of rainfall, it is not as wet as Mawsynram or Cherrapunji.

Therefore, the correct answer is option 4, Mawsynram.