Final answer:
The c. exponential distribution is a continuous distribution and is among the options given.
Step-by-step explanation:
The continuous distribution among the given options is the c. exponential distribution. The exponential distribution is often used to model the time between events that occur at a constant rate.
In the example given, the length of long-distance phone calls follows an exponential distribution with an average length of eight minutes. The exponential distribution is a continuous distribution because the random variable can take on any value within a given range.