Which of the following statements best describes how a corn plant comes to produce the bt toxin?
a. the bt gene is inserted into each plant cell, one at a time, by using a bacterial plasmid.
b. the bacteria containing the bt gene are sprayed onto the corn plants.
c. the bt gene is inserted into one plant cell by using a bacterial plasmid.
d. the bt gene is inserted into the soil and is taken into the corn plant through the roots.