Four (4) types of pleas are permissible in response to a complaint in the municipal court:
A. Guilty.
B. Not guilty.
C. Nolo contendere, subject to the approval of the court. The legal effect of such plea shall be the same as that of a plea of guilty, but the plea may not be used against the defendant as an admission in any civil suit based upon or growing out of the act upon which the criminal prosecution is based.
D. A former judgment of conviction or acquittal of the offense charged, which must be specially pleaded, either with or without the plea of not guilty. (1987 Code § 6-129)