Question: The Chengdu J-20 is what type of aircraft that is designed to avoid detection, and whose technology likely began in Germany during World War II?
Sentence (from "Stealth aircraft"): Stealth aircraft are designed to avoid detection using a variety of technologies that reduce reflection/emission of radar, infrared, visible light, radio-frequency (RF) spectrum, and audio, collectively known as stealth technology.
Relevant evidence: Yes