Although this option is free, there are two main problems with it.
Adsense accounts are free and the person with the adverts gets paid a very small amount each time one is clicked by a visitor. Many marketers, myself included, laughingly call this "Just Over Broke. https://telegra.ph/Problemy-z-silnikiem-samochodowym-i-ich-naprawa---Poradnik-03-12