[单选题]
It can be shown that the approximate age ofbos0ia9l hg6: tr i)lqdx: 6sd4he universe is 1/H, where H is the Hubble constant. Taking H) :lrdxiq4 6ds = 20 km/s/Mly, estimate the age of the universe, in years.
A. 15 thousand years
B. 15 million years
C. 15 billion years
D. 15 trillion years
