The fifth answer is correct, and as a matter of fact we have been here for quite some time. We are from the fifth planet orbiting the Algol star system and have had observers on earth for over three centuries. Our native language is unpronounceable to humans, so you may call us Algolians, but please do not confuse us with another alien race visiting your planet called Algoreans.
Unlike the Algoreans, our mission is observation only and non-interference. However just over a half century ago we did covertly provide assistance with your development of computer programming languages.