Laryngitis is inflammation of the voice box (larynx), leading to hoarseness or loss of voice. Pharyngitis is inflammation of the pharynx, causing a sore throat. Laryngitis primarily affects the voice, while pharyngitis primarily affects the throat.
The government audits McDonald's just like it audits any other company.
"Detecting" tax evasion can be a hard thing to do if you don't have the legal rights of a private investigator for instance. At any rate, tax evasion is not "detected" in the sense that there are certain behaviors to look for, evaders are caught.
An audit trail is a formal record or log of the financial transactions of an organization.