rigid (Adj.) : inflexible, difficult to change; very strict.
flexible (Adj.) : able to bend; able to change.

Correct Option: B

rigid (Adj.) : inflexible, difficult to change; very strict.
flexible (Adj.) : able to bend; able to change.

vice (N) : evil or immoral behaviour.
virtue (N) : high moral attitude; good quality.

Correct Option: B

vice (N) : evil or immoral behaviour.
virtue (N) : high moral attitude; good quality.

certain (Adjective) : having no doubts
dubious (Adjective) : doubtful; uncertain; uncertain
delirious (Adj.) : extremely excited and happy
laconic (Adj.) : using only a few words to say something

Correct Option: D

certain (Adjective) : having no doubts
dubious (Adjective) : doubtful; uncertain; uncertain
delirious (Adj.) : extremely excited and happy
laconic (Adj.) : using only a few words to say something

decrease (V) : to make or become smaller.
heighten (V) : make stronger; strengthen; intensify; increase.

Correct Option: B

decrease (V) : to make or become smaller.
heighten (V) : make stronger; strengthen; intensify; increase.

civilized (Adj.) : wellorganized socially with a very developed culture and way of life
barbarous (Adjective) : coarse; extremely cruel and shocking; uncivilized; showing a lack of education and good manners
savage (Adj.) : aggressive and violent ; causing great harm

Correct Option: B

civilized (Adj.) : wellorganized socially with a very developed culture and way of life
barbarous (Adjective) : coarse; extremely cruel and shocking; uncivilized; showing a lack of education and good manners
savage (Adj.) : aggressive and violent ; causing great harm