Final answer:
President George Washington's first cabinet consisted of four main department heads, but the number could be interpreted as five if including the Attorney General. In 2016, the cabinet had grown to fifteen department heads.
Step-by-step explanation:
The first cabinet under President George Washington consisted of four department heads, which were the Secretary of State, the Secretary of the Treasury, the Secretary of War, and the Attorney General. However, the correct number of department heads in this context might be five as the question seems to consider the Attorney General a cabinet head. By contrast, the cabinet in 2016 consisted of fifteen department heads. Over time, the US cabinet has evolved to include a wider range of executive departments, reflecting the increasing complexities of governing a modern nation-state.