correct answer is: c) 1\;:\;5

Explanation

We know, 1 hour = 60 minutes.
\therefore 1 hour 15 minutes =\left(60+15\right) minutes.
\rightarrow 75 minutes.
Now,
Ratio of 15 minutes and 75 minutes is :
\rightarrow\large\frac{15}{75} or \large\frac{1}{5} or 1\;:\;5
Ans: 1\;:\;5\;.

Alternative phrasings for this particular math query are:

1. What is the ratio between 15 minutes and 1 hour 15 minutes?
2. Find the ratio represented by 15 minutes to 1 hour 15 minutes.
3. What ratio does 15 minutes bear to 1 hour 15 minutes?