Koine Greek

... was, according to Wikipedia, "the common supra–regional form of Greek spoken and written during the Hellenistic period, the Roman Empire, and the early Byzantine Empire, or late antiquity."

Wikipedia has a link from the phrase "common supra–regional form", which points to a page entitled Koine language. Here we learn that "a koiné language is a standard or common language or dialect that has arisen to prestige or dominance as a result of the contact, mixing, and often simplifying of two or more mutually intelligible varieties of the same language."

In other words, Koine Greek may well be the language that the New Testament was written in, but it is not a language in its own right. If I'm reading Wikipedia correctly, it seems that any language can potentially have a koine version, and to refer to any particular language simply as "koine" is quite meaningless.

In other words, anyone that answers "Koine" to this question is most definitely showing off, and doesn't (IMHO) deserve the points.

What's more, Wikipedia tells us that Koine Greek is also known as Alexandrian dialect, common Attic, Hellenistic or Biblical Greek. So if we're allowing alternative answers, any one of these should be acceptable.