Which of these languages uses characters instead of an alphabet?

Chinese, which uses logograms - characters standing for meaningful units rather than sounds. There are tens of thousands, though literacy in practice needs perhaps three to four thousand, and most are built from a semantic component hinting at meaning plus a phonetic component hinting at sound.

The consequence is that writing floats free of speech. Mandarin, Cantonese and Hokkien are not mutually intelligible - speakers cannot converse - but the written language is largely shared, so the same page can be read aloud in mutually incomprehensible ways and understood identically. That is a large part of how a single administration held together across a continent for two thousand years, and it also means classical texts remain readable in a way that Old English is not to us.

The cost is learning it, and technology made that briefly look fatal. Typewriters were monstrous and early computing had no answer at all, which drove the simplification of thousands of characters in mainland China in the 1950s - Taiwan and Hong Kong kept the traditional forms, so the same language now has two written standards. The problem then evaporated: phonetic input methods mean a modern user types the sound and picks the character, and Chinese is now among the fastest languages to enter on a phone.