Answer:
The correct answer is all of them. The President, as Chief Executive, and Head of State, has to assist to ceremonies of various natures, both at home and abroad, he oversees agencies that are part of the Executive branch, oversees law enforcement agencies, has the legislative power to veto Congress´s legislations that are deemed unconstitutional and is in charge of making sure that the laws passed by Congress are enacted correctly by his staff and secretaries through different methods, like executive orders. These are all functions that have been given to the President of the United States by the Constitution and as Chief Executive, which means that there is no higher position than his/hers, as head of government, he/she has the task, as well, to ensure that his executive members are all working properly. In other words, he is also the head manager of the government and the state.