Experiments in environmental toxicology can sometimes be manipulative experiments in which the researcher actively chooses and manipulates the independent variable. in hunt's study, for example, dosages of bpa were manipulated and the effects were measured. in manipulative studies, the researcher controls all the other variables in the experiment, so any health effects observed in the test subjects can be attributed to differences in the independent variable.

The answer is true.

In a manipulative field experiment, the specialist first adjusts levels of the predictor variable (or factor), and afterward estimates how at least one factors of intrigue react to these modifications. These outcomes are then used to test theories of circumstances and end results. For instance, on the off chance that we are occupied with testing the speculation that reptile predation controls creepy crawly thickness on little Caribbean islands, we could change the thickness of reptiles in a progression of fenced in areas and measure the subsequent thickness of arachnids (e.g., Spiller and Schoener 1998).  

answer would be b, a tariffs main purpose is to protect domestic production and jobs.

answer; the sound of a train whistle makes a woman think of an old friend; //

the smell of grass makes a by feel that spring is the best; (apex);