Question

Read the sentence. When the Spaniards decided to conquer Mexico they appointed Hernan Cortes to lead the army. Which answer shows proper comma usage? When the Spaniards, decided to conquer Mexico, they appointed Hernan Cortes to lead the army. When the Spaniards decided to conquer Mexico they appointed Hernan Cortes, to lead the army. When the Spaniards decided to conquer Mexico, they appointed Hernan Cortes to lead the army. When the Spaniards decided, to conquer Mexico, they appointed Hernan Cortes to lead the army.

Answer 1

The third sentence is the correct answer - When the Spaniards decided to conquer Mexico, they appointed Hernan Cortes to lead the army.
Given that there is an inversion in this sentence (the dependent clause is placed before the independent one), comma has to be placed after the dependent clause, and before the independent one. So, the comma should be after when the Spaniards decided to conquer Mexico.