The "Show Answer" button shows up for a problem after someone incorrectly answers it, even though it has the "Show Answer" value set to "answered". Based on the documentation at http://edx.readthedocs.io/projects/edx-partner-course-staff/en/latest/course_components/create_problem.html#show-answer, this is not the expected behavior.
Show the answer only after the learner answers the problem correctly.
If the problem can be, and is, reset, the answer is not shown until the learner tries the problem again after resetting. (When a learner answers a problem, the problem is considered to be both attempted and answered. When the problem is reset, the problem is still considered to have been attempted, but is not considered to be answered.)"
This is instead working more the way "Attempted" works, so is redundant in its current state.
Screenshots illustrate "Show Answer" setting as set for first problem (Checkboxes) as the instructor in Studio, and also the LMS side as a learner after incorrectly answering the same question and the "Show Answer" button displaying at that time.
1. As an instructor, go to a unit in your course.
2. Add a problem component (I only tested problems under "Common Problem Types" in the problem component).
3. Click on "Settings".
4. Change "Show Answer" value to "answered".
5. Save your changes to the problem and publish the unit.
6. As a learner, go to that unit in the course.
7. Select an incorrect answer option.
8. Submit your answer.
You will see the correctness indicator show that your answer was wrong, and nothing more.
You see the correctness indicator showing that your answer was wrong, but you also now see the "Show Answer" button.