Why Was the Legislative Branch of Government So Important to the Founders

Why was the legislative branch of government so important to the Founders?

A) Congress would have the authority to make new laws, and that authority is central to any government.
B) Congress would be able to choose the president, who would have nearly all the power within the federal government.
C) Congress had to be structured in a way that benefitted both the large, populous states and the smaller states.
D) Congress would be the only governing body with the authority to tax citizens, so they wanted to carefully limit it.