Answer:
1. male toads collected from the suburbs
Explanation:
<em>The control group in this case would the </em><em>male toads collected from the suburbs.</em>
In an experiment, the control group represents a group that receives every other treatment as the experimental group except that of the variable whose effect is the main aim of the experiment.
In observational study, the control group is selected based on a randomly chosen area depending on the variables being examined.
In this case, the researchers are out to investigate whether the reproductive problems observed in the population of cane toads are due to poisons from chemicals associated with agriculture. The control group would be those that are sure not to be a recipient of the poisons associated with agricultural chemicals. Hence, the population of toads close to agricultural sites would form the study group while those far from agricultural sites would represent the control group.
<u>Therefore, the male toads collected from the suburbs would be the control group. </u>