What governs an artist’s choice of size?

The thins that govern artist's choice of size is the purpose and the intended location of the artworks.

If the purpose is to attract attention or creating a landmark, the artist could create a bigger Art Size. If the artist aim for elegance and simplicity, the size tend to be smaller

Abecause they about to fight. and it can’t be d because they always wanted independence. can’t be b because can’t negotiate. so it’s a