It ____ you to at least 50% off the regular price of either frames or lenses when you buy both.
A) presents B)entitles C)credits D)tips

I think the sentence meaning is if I buy frames and lenses together I will have at least 50% discount price of either frames or lenses.
The C credit and D tip arenot the want. I think the present is the answer because the present word has the largess meaning. Now I buy both so the vender will give me a largess.
But the answer is B. I can't understand it. Emotion: sad
You seem to understand the meaning of the sentence. Maybe the meaning of "entitle" is the problem.

"entitles you to" means "gives you the right to (receive)", as in

This ticket entitles you to a free drink with your order of a hamburger and fries.

(I don't know what you were trying to say with "largess". )
I can understand your confusion here.

I assume that the sentence refers to a money off voucher.

A voucher cannot 'present' you with anything; it may be a gift in itself, someone may present it to you, but the voucher cannot give you a gift as it is just a piece of paper.
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Hi, CalifJim, thank you very much for your clear explanation.

why did I say "largess"? Because the "present" has the "make a gift to" meaning.
 nona the brit's reply was promoted to an answer.
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