Consider the following description of something you may see in a database: Oak trees have become more and more sophisticated through evolution. This time, they have taken a step forward. Each acorn generated by the oak tree comes with an identifying marker for scholars to help track them. One scholar has decided to make a database like this:
One table consists of the acornID and the Tree that produced it. Another table consists of a squirrelID, squirrelName, and an acornID (because this scholar has some squirrels who work for her to collect the acorns, but they do not get them all). She names all the squirrels, but she is forgetful. As such, it is possible that she may have repeated a name. Describe the following types of keys in this database by defining them and then giving an example of them from the database:

a. Secondary Key
b. Primary Key (do so for each table)
c. Foreign Key (be sure to complete the description of this one as it has multiple pieces)