I think we'd all agree the correct answer is E, but I had multiple math teachers regrade my tests with higher scores after I pointed out that there were multiple correct solutions to the problem. In several cases, other students had provided the same solution I had but assumed they were wrong because the graded test said so. And these were tests the teachers had used for years. So let's change the question: if you're a student taking this test, how do you make sure that you didn't lose points because the test writers thought that C was the right solution? Or do you just trust public educators to grade you correctly?
Well the incident that sticks out in my memory was actually the kind where you show your work and circle your final answer. And as long as you get that work back and are confident you can then re-check the problem and can appeal with the teacher. That's a little harder to do with multiple choice because you have to replicate how you arrived at the answer you did, but the bigger problem is a general process problem. Standardized tests often don't yield individual results to the test-taker, so you're entirely dependent on the test writers and whatever review they seek out to ensure it's correct. And standardized test writers have been known to have some pretty BS questions (there was an article around where an actual author whose writing was used as material in a standardized test didn't know the answer to the questions being asked of students).
