The question asks to identify the riverine port among the options given on a hypothetical map of India. Riverine ports are ports built along a river, facilitating inland water transport. They are different from sea ports, which are located on a sea coast.

Option 4 is specified as the correct answer, which indicates that the location marked as `4` on the map represents a riverine port. This could be Kolkata port, for example, which is a well-known riverine port in India situated on the Hooghly River.

Option 1, 2, and 3, hence, represent other types of ports which could be sea ports or dry ports on the outline map of India (for example, Mumbai, Chennai or Tuticorin, which are sea ports). The specific identification of these ports would rely on the exact markers on the actual map.

It`s important for students to understand the geographical locations of different types of ports given their economic and strategic importance.