The correct answer is option C.
An inter-state supply is a supply of goods or services where the supplier and the recipient are located in different states. In option C, the supplier is located in Delhi and the place of supply is in Chandigarh. Since Delhi and Chandigarh are different states, this is an inter-state supply.
Option A is not an inter-state supply because the supplier and the recipient are located in the same state. Option B is not an inter-state supply because the place of supply is in an SEZ. SEZs are treated as a separate geographical area for the purposes of GST. Therefore, a supply to an SEZ is not considered to be a supply between two different states.