Since <em>ostentatious </em>and <em>modest </em>are antonyms, their meanings are completely opposite, we need to find a pair of words which also denote something different. The correct answer is reticent:talkative, because reticent is shy, and talkative is obviously not.
Teasing can seem playful and is most commonly between friends. Bullying is kinda like teasing except that someone may be getting hurt physically or emotionally and has no way of stopping it.