The correct answer to this open question is the following.
All human labor was used to build everything in the city. One large stone took up to fifteen men to move it.
That's how hard it was to move heavy rocks to built the pyramids of Mesoamerican places such as Tenochtitlan. It was the capital of the Aztec Empire, located in modern-day downtown México City. In that time, the place was built over Texcoco Lake, and the Aztecs built water channels that connected other close towns such as Mixcoatl, Tlalpan, or Tlatelolco.
The correct answer is "They advise the President on policy matters". Independent executive agencies are technically part of the executive branch, but the are not directly controlled by the President of the United States and they do not advise the President. The Executive Office of the President (EOP) are the agencies that advise the President in policy matters.