Advanced patterns for testing — quiz

Your test framework supports three environments — dev, staging, prod — and `currentEnv` should only ever hold one of those values. Which declaration prevents typos like `"stagging"` at compile time?

• let currentEnv: string = "dev"
• enum Env { Dev = "dev", Staging = "staging", Prod = "prod" }; let currentEnv: Env = Env.Dev
• let currentEnv = "dev"; const ENVS = ["dev", "staging", "prod"]
• let currentEnv: any