What is a polite euphemism for being short?
a.) altitude challenged
b.) not tall
c.) small and tiny
d.) with little height

A polite euphemism for being short is Altitude challenged

Explanation:

A euphemism is a different form to mention something that could be considered offensive by others, especially for the ones that are affected by the situation or condition, then Altitude challenged or vertically-challenged are common euphemisms to describe someone being short if it is considered a sensitive topic.

pre owned vehicle

Explanation:

a pre-owned car thats the answer

A

Explanation:

because what's the best way to tell them the truth

altitude challenged

Explanation:

I like this car but doesn't it seem a little old for me?

Or you can use:

This is a nice car but I don't want it to break down on me.

People tend to approach something with excessive precaution and indirectly when they feel embarrassed about it, using substitute words or indirect expressions to avoid situations they're not capable of managing, thus people use euphemisms to protect themselves; so to avoid appearing as offensive when addresing a short stature person or shorter than them or the normal, people use the expressions:

"Vertically challenged" or "Altitude challenged".

Explanation:

To make it polite you can use old or used  

adverb is the answer i believe.