Serena is cycling from dance class to her home. The equation shows Serena's distance (y), in miles, from her home after x minutes:

y = 16 − 6x

What does the number 16 in the equation represent?

Serena's distance from home when she begins cycling
Serena's distance from the dance class when she begins cycling
The speed at which Serena is cycling from the dance class to her home
The rate of change of Serena's speed while cycling from the dance class to her home