What does HiRobo look like?

Question

1. He is long and strong.
2. His arm is long and strong.
3. He has a long and strong arm.
4. He has a long strong arm.

(Are the answers all correct? What about #3 and #4? Which one is correct? are both OK?)

Answer 1

All of them are correct except --

4 should have a comma to replace "and."

a long, strong arm