A state statute requires any person licensed to sell prescription drugs to file with the State Board of Health a report listing the types and amounts of such drugs sold if his or her sales of such drugs exceed $50,000 during a calendar year. The statute makes it a misdemeanor to "knowingly fail to file" such a report. Nelson, who is licensed to sell prescription drugs, sold $63,000 worth of prescription drugs during 1976 but did not file the report. Charged with committing the misdemeanor, Nelson testifies that he did a very poor job of keeping records and did not realize that his sales of prescription drugs had exceeded $50,000. If the jury believes Nelson, he should be found 
guilty, because this is a public welfare offense.  guilty, because he cannot be excused on the basis of his own failure to keep proper records.  not guilty, because the statute punishes omissions and he was not given fair warning of his duty to act.  not guilty, because he was not aware of the value of the drugs he had sold