How might you greet someone in Mandarin Chinese?

Trivia: How might you greet someone in Mandarin Chinese?

Bù kèqì
Wǎn ān
Nǐhǎo
Xièxiè

Correct Answer: Nǐhǎo

So why is this answer correct? : “Nǐhǎo” is pronounced “nee how” and simply means “hello.”