Aaron wants to download a new program from the internet and install it on his computer. what is the safest way for him to do this

First, ask friends and family if they have gotten infected by a possible virus (It is most common on .exe files)
Seccond, use a file scanning service like spybot or Avast to check to see if the file is infected, if so, delete it ASAP
Third, good luck with web safety

You forgot to add the possibilities. we don't know the options from which to choose.