Explanation:

- The word "discern" means to recognize or understand something clearly or to distinguish differences.

- Option 1: Regulate - Means to control or maintain the rate or speed of something so that it operates properly. It is not a synonym for discern.

- Option 2: Analyze - Means to examine something in detail for the purpose of explanation or interpretation. This can relate to discernment because it involves careful observation and understanding, but it's not a direct synonym.

- Option 3: Control - Means to have power over something or to guide it. This is not related to discernment.

- Option 4: Discriminate - Means to recognize a distinction or differentiate. This is a closer synonym to discern, as both involve perceiving differences.

Option 4: Discriminate is the correct answer.