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.

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.