Final answer:
Iago's final soliloquy reveals that he plans to use Emilia to obtain Desdemona's handkerchief, which is pivotal to his plot in Shakespeare's Othello.
Step-by-step explanation:
Iago's final short soliloquy indicates that he will use his wife Emilia for a very specific and crucial part of his plan. The correct answer is c. Emilia is tasked with obtaining the handkerchief as part of Iago's scheme. This handkerchief is a significant prop in Othello, as Iago plans to use it to create evidence of an affair between Desdemona and Cassio, thereby setting off a chain of tragic events due to Othello's jealousy.