A. Within a reasonable time, the Commissioner shall make and serve upon each party his decision, which shall become final upon the 20th day after service thereof, unless exceptions are filed thereto, as provided in R. 71-220. The decision of the Commissioner shall include:

1. (1) A statement of findings and conclusions, with reasons and bases therefor, upon each material issue of fact, law or discretion presented on the record, and

2. (2) The appropriate rule, order, relief, or denial thereof.

   The decision of the Commissioner shall be based upon a consideration of the whole record and shall state all facts officially noticed and relied upon. It shall be made on the basis of a preponderance of reliable and probative evidence.