Which amongst the following are highly eroded by the agents of gradation and have gentler slopes, rounded tops and sculptured domes?

1. Young fold mountains
2. Old fold mountains
3. Residual mountains
4. Volcanic plateaus

Mountains which are subjected to weathering and erosion for a long time are lowered down:

1. Old fold mountains
2. Volcanic plateaus
3. Relict mountains
4. Intermontane plateaus

The plains that are formed by the deposition of materials which have been brought by various agents of transportation:

1. Structural plain
2. Depositional plain
3. Plain
4. Landform

A piece of land reclaimed from the sea or lake:

1. Sealand
2. Iceland
3. Lakeland
4. Polder