After-school activities running late entails that the buses will run late. The buses running late is a sufficient condition for either Carlos and Deandra getting home late or Edna missing dinner. Either after-school activities run late but Carlos doesn't get home late, or after-school activities run late but Deandra doesn't get home late. So, Edna misses dinner.
-Working backward from the conclusion of this argument, which of the following is the most likely justification of the last step of the derivation?
A) MP
B) Simp
C) DN
D) DS
E) HS

Question

Quizplus · Accepted Answer

The last step of the argument is a disjunctive syllogism (DS), which concludes that Edna misses dinner. This is because the given premises establish that if the buses run late, either Carlos and Deandra will get home late or Edna will miss dinner. The argument then presents two cases where the buses run late but Carlos or Deandra do not get home late, leaving only the possibility that Edna misses dinner.

After-School Activities Running Late Entails That the Buses Will Run