The correct answer is option 3, the Durand Cup. The Durand Cup is the oldest football tournament in Asia. It was first organized in 1888 and is still being held annually.

Option 1, the Federation Cup, is not the oldest football tournament of Asia. The Federation Cup is a football tournament organized by the All India Football Federation (AIFF) and was first held in 1977.

Option 2, the Santosh Trophy, is also not the oldest football tournament of Asia. The Santosh Trophy is a football tournament in India that has been held since 1941.

Option 4, the Rovers Cup, is also not the oldest football tournament of Asia. The Rovers Cup was a football tournament in India that was held from 1891 to 1997, but it is not considered the oldest in Asia.

Therefore, the Durand Cup is the oldest football tournament of Asia, with a history dating back to 1888.