Answer:
3.
Step-by-step explanation:
Under the emperor Wu of Han, iron and salt were important products, which in early empire were produced and sold by rich merchants. But under emperor Han, he made iron and salt a state monopoly.
Perceiving the production of iron and salt by rich merchants a threat on state, he took this step of making iron and salt state monopoly. By making these two products as a state monopoly, states started earning large profits making the empire financial capable to support the various campaigns by the emperor.
Therefore, the correct answer is option 3.