Regulatory agencies are sometimes described as having some of the powers of all three branches of government. when a regulatory agency fines a business for not following a government rule, it is acting much like which branch of government?

The answer is: The Legislative branch.

Explanation:

The United States Constitution mentions only three branches of government: legislative, executive and judicial, articles I, II and III. Agencies are not mentioned in the Constitution, although federal agencies are sometimes referred to as "the fourth branch of government."

The Supreme Court has recognized the legitimacy of federal administrative agencies: Government, state or federal units, which have specialized experience and authority in some area of the economy, to make rules that have the same binding effect as statutes by Congress.

Administrative agencies have the responsibility to carry out a specific task or achieve a goal or set of goals. They must not remain, in acting because they have been granted legislative powers.

The answer is: The Legislative branch.