# Sludge volume index is defined as the ratio of_______________?

**Sludge volume index is defined as the ratio of_______________?**

**A. percentage of sludge by volume to percentage of suspended solids by weight(Correct)**

B. percentage of sludge by volume to percentage of total solids by weight

C. percentage of suspended solids by weight to percentage of sludge by volume

D. percentage of total solids by weight to percentage of sludge by volume