Which statement accurately describes an aspect of promises?

Promise.prototype.then(onFulfilled?, onRejected?) defines both parameters as optional (indicated by the “?”). A developer may pass only one, both, or neither argument; the method still returns a new promise that adopts the appropriate state.

B. A then() can be chained after catch(); promises remain chainable.

C. then() always returns a new promise, leaving the original promise untouched.

D. If a then() callback omits an explicit return, the next then() receives undefined, not the previous result.

1. ECMAScript 2023, §25.6.4.3 Promise.prototype.then, Note 1 (both parameters optional, returns new Promise).

2. Stanford CS193p “Modern JavaScript”, Lecture 7 slides 15-17 (promise chaining, optional handlers).