JavaScript Property Descriptors Quiz: writable, enumerable and configurable

JavaScript Property Descriptors Quiz: writable, enumerable and configurable

Choose one answer. Each attempt draws 10 of 20 questions; the practice pass mark is 8/10. Original topic practice, not an official exam. Object.defineProperty defaults, strict-mode failures, accessors and shallow freezing.
1 of 10
What is printed?
JavaScript
const o = {};
Object.defineProperty(o, 'x', {value: 7, enumerable: true});
console.log(JSON.stringify(Object.keys(o)));