Fact 1: Abalance is used for measuring mass of an object.

Fact 2: Bears are proportionally weighted for use on a balance for measurement discoveries.

Given the two facts above, answer the question "Bears are proportionally weighted on a balance for discovering what?" with the following options: 
- size
 - traits
 - mass
 - age
 - energy
 - forces
 - SNPs
 - shape


 

   mass      