Francis Crick's theory of directed panspermia states that __
a. primitive life forms floating about in deep space accidentally landed on our planet.
b. the slow evolution of the first cell was followed rapidly by spread of its offspring around the earth.
c. life was "seeded" on this planet by a civilization of life forms superior to us
d. the earliest organisms on earth were able to freely inter-mate with a wide variety of other such forms to produce novel offspring.
e. sperm cells find their corresponding egg cell by a signal emanating from the egg cell itself.