U-235,the Isotope of Uranium That Is Essential for Operating Nuclear

Multiple Choice

U-235,the isotope of uranium that is essential for operating nuclear power plants,is ____________.

A) the most common of the naturally occurring isotopes of uranium
B) heavier than the other well-known isotope of uranium
C) so rare even in uranium oxide deposits that uranium ore must be processed to enrich the proportion of U-235 to all uranium
D) created by "breeder reactors" as well as produced during nuclear (atomic bomb) explosions