The correct answer is: 770 AD.
The Sudh Mahadev temple is a Hindu temple located in the village of Sudh Mahadev, in the Chamoli district of Uttarakhand, India. The temple is dedicated to the god Shiva. The temple is believed to have been built by Raja Gambhir Chand in the 8th century AD. The temple is a fine example of the Nagara style of architecture. The temple is built on a high platform and has a pyramidal shikhara. The temple has a number of sculptures and carvings on its walls. The temple is a popular tourist destination.
Option A: 670 AD is incorrect because the Sudh Mahadev temple is believed to have been built in the 8th century AD.
Option B: 770 AD is the correct answer because the Sudh Mahadev temple is believed to have been built by Raja Gambhir Chand in the 8th century AD.
Option C: 870 AD is incorrect because the Sudh Mahadev temple is believed to have been built in the 8th century AD.
Option D: 970 AD is incorrect because the Sudh Mahadev temple is believed to have been built in the 8th century AD.