Sweeten is to make something sweet , Race is competition and Deliver means convey .

Correct Option: A

Parley is to discuss, sweeten is to make something sweet.

Tarnish is to lose lusture , Ambitious means forceful and
Challenging is to provocative.

Correct Option: C

Browbeat is to scare someone by powerful words, timidate is also to overpower or influence greatly, incite fear. Tarnish is to lose lusture.

Permit is to allow, admit is to accept, restrict is to stop or control.

Correct Option: B

Waive is used as the discounts or relaxations given in a loan or a debt, e.g., ‘I will waive off the interest for last two months’ thus the synonym will be release, permit is to allow, admit is to accept, restrict is to stop or control.

Friendliness is always harmonious, nebulous means not in a definite shape, abominable is hateful, delicate is soft.

Correct Option: C

Amicable means friendly and harmonious means an agreement and working together with perfect cooperation, friendliness is always harmonious, nebulous means not in a definite shape, abominable is hateful, delicate is soft.

lasting or existing forever ; without end.
used to emphasize expressions of admiration, gratitude, etc.

Correct Option: B

Adjective
1.
lasting or existing forever ; without end.
"the secret of eternal youth"
synonyms: everlasting, never-ending, endless, without end, perpetual, undying, immortal, deathless, indestructible, imperishable, immutable, abiding, permanent, enduring, infinite, boundless, timeless; More
2.
used to emphasize expressions of admiration, gratitude, etc.
"to his eternal credit, he maintained his dignity throughout"