If you believe you did not commit the violation then you should select box three and have a contested hearing. Unless you request the officer to be subpoenaed, the procedure at the hearing will be for the Judge to read the sworn statement of the officer. Then you may testify or present any evidence or witnesses that you wish.
If you want to have the officer present, you must advise the Clerk at least fourteen days in advance of your court date. As a result of a contested hearing, the penalty may stay the same, be reduced, or the ticket dismissed. In the event you have subpoenaed witnesses you may be required to pay court costs. A contested infraction hearing is a civil case and the Judge will decide the case based on the preponderance of the evidence.