Word choice (diction), word order (syntax) ,and sentence length are all elements of what?

text features
tone
style

The correct answer is style.

Style is a distinctive use of language, in terms of vocabulary, the arrangement of sentences, as well as their length. It is unique to a situation, a writer/speaker, a decorum (setting). When you write a novel, you will use a different style than when writing a newspaper article, for example. A novel can use flamboyant style, full of adjectives, long sentences, unusual word order, etc. A newspaper article, on the other hand, demands terse and informational style, with short sentences, straight to the point.