Which word would best describe a conversation that involves playful teasing?

The word "banter" aptly describes a conversation that involves playful teasing because it specifically refers to light-hearted and witty exchanges between people. Banter is characterized by a good-natured spirit, where participants engage in teasing comments or playful dialogue without any intention of causing harm or offense. This type of interaction is often friendly and fosters a jovial atmosphere, making "banter" the ideal choice for describing such conversations.

In contrast, the other options do not convey the same sense of light-heartedness and playfulness. "Banality" relates to something being unoriginal or dull, which does not fit the lively nature of playful teasing. "Barter" refers to the exchange of goods or services, which is unrelated to conversations or teasing. "Benignity" signifies a gentleness or kindness, but it lacks the playful element that defines banter.

Thus, "banter" is the most suitable word to capture the essence of light-hearted teasing in conversation.