Among the options you've provided, ballistic stretching is generally considered to be the most dangerous. Ballistic stretching involves using momentum to force a body part beyond its normal range of motion, which can increase the risk of injury, particularly to muscles and tendons. It can lead to strains or tears if the muscles are not adequately warmed up.
The other stretches you mentioned—trunk twist, straddle stretch, and quadriceps stretch—can be safe when performed correctly and with proper technique, although they may still pose risks if done improperly or without adequate warm-up. It's important to focus on static and dynamic stretching practices that improve flexibility without excessive risk of injury. Always consult with a fitness professional if you're unsure about the safety of specific stretches.