<span>A) only three house flies were collected for an experiment
</span><span>Errors are what makes your measurement invalid and unreliable. There are two types of error which is called the systematic error and the random error. Each error has different sources. Words that were mentioned –invalid and unreliable are very important key aspects to determine that your measure is truly accurate and consistent. Some would recommend using the mean method, doing three trials in measuring and getting their mean, in response to this problem.</span>
Effectors are muscles, organs, or other structures that receive signals from the brain or control center. When an effector receives a signal from the brain, it changes its function in order to correct the deviation.