Parts of a country behind the coast or a river’s banks:

Parts of a country behind the coast or a river’s banks:

A. Swamps
B. Hinterland
C. Isthmuses
D. None of these

One word substitute is Hinterland.
Swamps: an area of low-lying, uncultivated ground where water collects.
Hinterland: the remote areas of a country away from the coast or the banks of major rivers.
Isthmus: a narrow strip of land with sea on either side, forming a link between two larger areas of land.

Choose the most suitable word: An office or post with no work but high pay:

Choose the most suitable word: An office or post with no work but high pay:

A. Honorary
B. Sinecure
C. Gratis
D. Ex-Officio

Honorary: conferred as an honour, without the usual requirements or functions.
Sinecure: a position requiring little or no work but giving the holder status or financial benefit.
Gratis: without charge; free.
Ex-officio: by virtue of one’s position or status.

Through which light cannot pass?

Through which light cannot pass?

A. Dull
B. Dark
C. Obscure
D. Opaque

One word substitute is Opaque.
Dull: lacking interest or excitement.
Dark: with little or no light.
Obscure: not discovered or known about; uncertain.
Opaque: not able to be seen through; not transparent.

The original inhabitants of a Country.

The original inhabitants of a Country.

A. Aborigines
B. Citizens
C. Natives
D. Primitive

One word substitute is Aborigines.
Aborigines: a person, animal, or plant that has been in a country or region from earliest times.
Citizens: a legally recognized subject or national of a state or commonwealth, either native or naturalized.
Natives: a person born in a specified place or associated with a place by birth, whether subsequently resident there or not.
Primitive: relating to, denoting, or preserving the character of an early stage in the evolutionary or historical development of something.