A single$-$server queuing system has average time between arrivals of $30$ minutes and a service time of $10$ minutes each. Assuming Poisson arrivals and exponential service times, the utilization factor is approximately:

A$)0\mathrm{.}25.$

B$)2\mathrm{.}0.$

C$)0\mathrm{.}50.$

D$)0\mathrm{.}33.$