Three of the given four names share a certain relation whereas one is different. Select the option that is different from the rest.

Agartala, Imphal, Kohima, Silchar

Given: Agartala, Imphal, Kohima, Silchar

Analyzing the given names:
Agartala → Capital of Tripura
Imphal → Capital of Manipur
Kohima → Capital of Nagaland
Silchar → A city in Assam, not a state capital
Odd one out:
Silchar is different because it is not a state capital, whereas the others are capitals of northeastern Indian states.
Thus, the correct option is (a) Silchar.