The correct answer is: a) Surkotada
Surkotada is an archaeological site in the Kutch district of Gujarat, India. It is located on the bank of the Manhar River, about 150 kilometers from Bhuj. The site was excavated by the Archaeological Survey of India (ASI) from 1963 to 1965.
Surkotada is a Harappan site, dating to the Mature Harappan period (2600-1900 BCE). The site is known for its well-preserved remains of a fortified city, as well as its large number of artifacts.
One of the most important finds at Surkotada is the evidence of early horse domestication. The ASI found the remains of several horses at the site, as well as artifacts that suggest that the horses were used for riding and transportation. This evidence suggests that Surkotada was one of the earliest sites in India where horses were domesticated.
The other options are incorrect because they are not Harappan sites. Lothal, Dholavira, and Rojadi are all Indus Valley Civilization sites, but they date to a later period than Surkotada.