The porter respectfully assured the lady that he would take care of her baggage while she bought her ticket.

The porter said, "I will take care of your baggage while you buy your ticket, Madam."

The porter said, "I would take care of your baggage while you buy your ticket, Madam."

The porter said, "I would take care of your baggage while you bought your ticket, Madam."

None of these

The porter said, "I will take care of your baggage while you buy your ticket, Madam."

The sentence is in direct speech.

Present tense ("will" and "buy") is used because the event has not yet occurred, aligning with the porter’s respectful assurance.