The value of the Dollar appreciates versus the Euro. Who will benefit?

American importers which are importing from Europe will benefit.

Explanation:

Currencies are valued relatively i. e. in comparison to one another, so currency appreciation is increase in value of one currency versus another currency, so if dollar appreciates versus euro, that means less dollars required to buy 1 euro this will result in a benefit for American importers, as for imports of 1000 euros previously 800 dollars were required to pay off (when 1 euro = 0.8 $) but now only 700 dollars are required (as the currency rate is 1 euro = 0.7 $) so importers can buy foreign goods cheaply and this will reduce inflation in America.