No flaw. (A) tells us that some employees at Tedenco are not salaried, and then validly concludes that two salaried employees can’t be the only people who work at Tedenco.

No flaw. (B) establishes a conditional relationship that applies to Tedenco employees: If you’re an accountant, then you’re not a corporate attorney. It then validly concludes that someone who fails to follow this conditional statement must not work for Tedenco.

(C) establishes a conditional relationship that applies to companies: If your headquarters are in Canada, they can’t also be in Mexico. It then invalidly concludes that two companies that meet the necessary condition (headquarters not being in Mexico) also meet the sufficient condition (headquarters being in Canada). The stimulus also concludes the presence of a sufficient condition because of the presence of a necessary condition, so (C) matches.

No flaw. (D) establishes a conditional relationship that applies to corporate attorneys: If you represent Dumone, you can’t also represent Tedenco. It then validly concludes that the sufficient condition leads to the necessary condition.

No flaw. (E) tells us that there is no overlap between the members of two boards. It then validly concludes that both boards together must have at least ten members, since each board separately has at least five members.