Which of the following is a common greeting in Thai?

"Sawasdee" is indeed a common greeting in Thai, often used to say "hello" or "welcome." It is a multifunctional term that encompasses both the act of greeting someone and also conveying a sense of respect. The greeting can be used in various social situations, making it foundational in the Thai language and culture. Additionally, it is customary to accompany "sawasdee" with a gesture called the "wai," which involves clasping the palms together at the chest and bowing slightly, further emphasizing respect and politeness in Thai interactions.

On the other hand, "Khawp khun" translates to "thank you" and is used to express gratitude, while "Chai" means "yes," and "Mai pen rai" conveys a sense of "no worries" or "it’s okay." These phrases serve different purposes within conversations but do not function as greetings in the same way that "sawasdee" does.