[单选题]
It can be shown that the approximate age of ynpw a+ xd410swb83bethe universe is 1/H, wher ;vxen;ih2 qbpx9t+7de H is the Hubble constant. Taking H = 20 km/s/Mly, estimate b e9+phqxdit7;v xn ;2the age of the universe, in years.
A. 15 thousand years
B. 15 million years
C. 15 billion years
D. 15 trillion years
