How are a mole and a dozen similar?
a. each represents a certain mass of material.
b. each names a given number of objects.
c. each identifies a specific volume.
d. each measures a given number of amus.

The answer is indeed B but let me explain ti better. A mole is similar to a dozen, because both are words used to describe a specific number of countable things. For example: 
12 flowers  =1 dozen of flowers
6.02×1023 flowers= 1 mol of flowers
As you can see, this expresses a specific number of something

A mole and a dozen each names a given number of object .B.

It would be true sodium reacts with water in a violent way