The correct answer is Hemis.
Hemis Monastery is the largest and richest monastery in Ladakh, India. It is located in the Hemis National Park, about 45 kilometers from Leh. The monastery was founded in the 11th century by Rinchen Zangpo, a Tibetan Buddhist master. It is a Gelugpa monastery, which is one of the four major schools of Tibetan Buddhism.
Hemis Monastery is home to over 400 monks. It is a major tourist attraction in Ladakh. The monastery is known for its annual Hemis Festival, which is held in the summer. The festival is a major cultural event in Ladakh and attracts visitors from all over the world.
The other options are incorrect because they are not the biggest and richest monasteries in Ladakh. Alchi Monastery is a 12th-century Buddhist monastery located in the village of Alchi, about 30 kilometers from Leh. Spituk Monastery is a 14th-century Buddhist monastery located in the village of Spituk, about 5 kilometers from Leh. Shey Palace is a 17th-century palace located in the village of Shey, about 15 kilometers from Leh.