You are required to click "Yes, I accept" on the NDA screen to start your test. If you click "No, I do not accept" deliberately or by mistake, you will be prompted to change the option on the next screen. However, if you still click "No, I do not accept", the test will end. You will not be able to resume the test that day under any circumstances. Test centre or Online Proctor staff will not be able to do anything and you will lose the test attempt as well as forfeit the test fee.
