Greenwood is in his first full season with the senior team and has managed 15 goals in all competitions.
It is the best return for a United teenager since Wayne Rooney.
And Solskjaer believes the teenager is ready for an England first team call-up.
"When you play for Manchester United, I think that's a test that's good enough and difficult enough," said Solskajer to reporters after a 5-2 win against Bournemouth.
"If you can handle playing for United, then you can handle playing for any team and Mason's got the qualities that not many others have.
"So he could play for England full team or the U21s, I don't really mind. I know he's doing well for us and it's great to have him here.
"Mason's a naturally good finisher, so he'll always score goals. He's a humble boy, he wants to learn, he listens and he works hard. Mason is one of the best if not the best finisher I have worked with and seen. He is so calm."