The . . . . . . . . of the discussion is still not known.

The correct answer is: outcome.

An outcome is the result of an event or action. In the context of the question, the outcome of the discussion is the final result of the discussion, which is still not known.

The other options are incorrect because they do not accurately describe the result of an event or action.

• Effect is the change that is produced by an event or action.
• Output is the result of a process or operation.
• Product is the result of manufacturing or processing.