The difference between "mostly true", "misleading", and "false" is context, and responses are specifically not allowed to include any context. Even "true" has a little context, since few things can be said to be absolutely true. "Unknown" also isn't allowed.

What's 2 + 2? The answer must be one of the colors of the rainbow.

(People can draw their own conclusions, but the only coherent reason I can think of for the design of this experiment is to generate a misleading conclusion.)