Final answer:
The word that best completes the sentence is 'bel'.
Step-by-step explanation:
C'est un bel homme.
In French, the adjective 'beau' (meaning 'beautiful' or 'handsome') changes to 'bel' when it precedes a masculine noun starting with a vowel or a silent 'h'.
So, the correct word to complete the sentence is 'bel'.
Learn more about French grammar