Question

Which of the following choices is a sound argument?

Jane Austen is an author. Stephen King is an author. Therefore, I want to be an author.
All turtles are reptiles. The snake is not a turtle. Therefore, the snake is not a reptile.
All teachers wear vests. Mr. Gonzales does not wear a vest. Therefore, Mr. Gonzales is not a teacher.
Immortal human beings live forever. Benjamin Franklin died. Therefore, Benjamin Franklin is immortal.

Answer 1

All teachers wear vests. Mr. Gonzales does not wear a vest. Therefore, Mr. Gonzales is not a teacher.

Answer 2

The sound argument is this one:

All teachers wear vests. Mr. Gonzales does not wear a vest. Therefore, Mr. Gonzales is not a teacher.

If ALL teachers wear vests, then it means that everyone who is a teacher is wearing a vest: you can recognise a teacher by their vest. So someone who is not wearing a vest, such as Mr. Gonzales, is not a teacher.