Concept:A coastal plain is a low, level area that emerges when part of the sea floor along a continent is uplifted.
Explanation:The question describes a large expanse of low, flat land bordering a continent.
This land is formed by the uplift of part of the sea floor, which exposes it above sea level.
A deltaic plain forms at a river mouth from deposited sediment, not by uplift.
An outwash plain is created by glacial meltwater deposits.
A flood plain lies beside a river and is covered during flooding.
Only a coastal plain matches the idea of an uplifted, exposed sea floor beside a continent.
Answer:Coastal plain.