The best reason to stay positive before a test is to

get a better precentige

Explanation:

too much stress can cause a lower score

The best reason to stay positive before a test is to prevent all forms of anxiety.

Explanation:

Before taking a test, it is important to stay positive in order to prevent all forms of anxiety. Test anxiety is a term used to define a combination of tensions, fears, somatic and catastrophic thoughts that occur before taking a test, which can severely affect the performance of that person in the test. Anxiety, in all its forms, is characterized by the overwhelming presence of negative thoughts that lower our self-esteem and, in the scenario of taking a test, will prevent us from allowing our ideas and knowledge to flow freely. In order to avoid this situation, the student should focus on positive thoughts before going to the classroom, so that he/she is relaxed and does the best they can in the test.