Which two words are the closest synonyms?

Charitable and outrageous

Personal and sophisticated

Isolated and popular

Trademark and characteristic

Trademark and characteristic are the closest synonyms.

A trademark is a word, words or phrases legally registered to be used by a company.

Characteristic means typical of a person, place or thing.

And a trademark can be characteristic of a company. For example, the white 'check' sign is characteristic of the brand Nike.