The answer to #13 is C, that is the definition of a linear function. Rise/Run is the same as y-values/x-values, which is the slope. Linear functions have constant slope. This is the same thing as saying the ratios of the change in y-values to the change in x-values are equal.
For #14:
Let's find out how many people entered the park after 1 minute, then we can calculate for 30 minutes. In 2 minutes, 144 people entered the park.
[tex]\sf 144\div 2=72[/tex]
So in 1 minute 72 people enter the park. This is our unit rate. To find out how many people enter the park in 30 minutes, multiply it by our unit rate.
[tex]\sf 30\times 72=\boxed{\sf 2160}[/tex]
So 2,160 people enter the park after 30 minutes.
