Option A - Equivocation
It involves the use of a term, word or expression in multiple sense leading to a false conclusion.
Just like the example above, a feather is light (because it is not heavy) but not all feathers are light in terms of brightness and color. Therefore, the use of the word 'light' has brought about a false conclusion.
Equivocation-in this use of equivocation, the word light is first used as the opposite of heavy, but then used as a synonym of bright (the fallacy usually becomes obvious as soon as one tries to translate this argument into another language). because the middle term of this syllogism is not one term, but two separate ones masquerading as one (all feathers are indeed not heavy, but it is not true that all feathers are bright), this type of equivocation is actually an example of the fallacy of four terms.