(a) consume a drug, controlled substance or an intoxicating liquor, regardless of its alcoholic content, or be under the influence of an intoxicating liquor or drug, within six hours before going on duty or operating, or having physical control of a bus, or

(b) consume a drug, controlled substance or an intoxicating liquor, regardless of its alcoholic content while on duty, or operating, or in physical control of a bus, or

(c) possess a drug, controlled substance or an intoxicating liquor, regardless of its alcoholic content while on duty, operating or in physical control of a bus. However, this paragraph does not apply to possession of a drug, controlled substance or an intoxicating liquor which is transported as part of a shipment or personal effects of a passenger or to alcoholic beverages which are in sealed containers. 2. No motor carrier shall require or permit a driver to:

(a) violate any provision of subdivision one of this section; or

(b) be on duty or operate a bus if, by such person's general appearance or by such person's conduct or by other substantiating evidence, such person appears to have consumed a drug, controlled substance or an intoxicating liquor within the preceding six hours, or eight hours when such driver operates a school bus as defined by section one hundred forty-two of this chapter.