Which of the following relationships is NOT a function?

The number of calories burned is a function of the minutes spent running.

The age of a tree is a function of the number of rings in its trunk.

A person's favorite food is a function of their age.

The perimeter of an equilateral triangle is a function of its side length.

The height of a building is a function of the number of floors it has. What is the output (dependent) variable in this relationship?

The year the building was constructed