Viruses only attack certain kinds of cells. in other words, they are specific. this is due to

a
their size
b
their reproduction
c
the shape of receptors on their outer covering
d
a, b and c are all correct

That is the correct answe

The soviet union beat the us to the first successful launch, with the october 4, 1957, orbiting of sputnik 1, and later beat the us to have the first human in earth orbit, yuri gagarin, on april 12, 1961. the "race" peaked with the july 20, 1969, us landing of the first humans on the moon with apollo 11