Why does a sounding board on a musical instrument produce louder sound?

Why does a sounding board on a musical instrument produce louder sound?1. A sounding board with large surface isable to set more air vibrating, so the ampli-tude of the produced sound will increase.2. A sounding board with large surface vi-brates with higher frequency, so the ampli-tude of the produced sound will increase.3. A sounding board with large surface hasgreater intertia, so the pitch of the producedsound will increase.4. A sounding board with large surface hasgreater intertia, so the pitch of the producedsound will decrease