I can see that you have a private single-user subscription rather than one that is allocated by a teacher (or course provider). In this case you do not have an attached teacher who can grade your work.
Many schools, colleges, universities and corporations have multi-user subscriptions. In this model the teacher allocates an individual student account to each student. While your private single-user subscription provides both the Exercise and Exercise Answers, a teacher is able to switch off the answers so that students only see the Exercise (and not the answers).
These settings are available in Settings tab of the Student/Teacher console.
If you are currently in full or part time education you may wish to ask your educational establishment to take out a multi-user subscription so that they can grade your work. You can find a short video showing how our multi-user accounts work and are administered here: