Final answer:
The correct options to complete the sentence are 'ethical' and 'legal,' implying that advertising false skills is against both morality and the law.
Step-by-step explanation:
The correct phrase to fill in the blanks in the given sentence would be: "It is neither ethical OR legal to advertise false skills and specialties." The question is related to morality and the rules governing professional conduct. Advertizing false skills or specialties is not only unethical, as it deceives others by misrepresenting one's abilities, but it could also be illegal, depending on the circumstances and local laws, as it can constitute false advertising or fraud.