Carlos is trying to figure out the best place to put his router in order to het the best signal. which is not an independent variable? a) distance from the wall b) signal strength at the computer c) the number of walls between the router and computer d) the number of devices on the router

B) signal strength at the computer

Explanation:

The independent variable in the experimental setup can be changed or manipulated so as to know it's influence over the dependent variable which is the outcome of the experiment.

Here, the signal strength of the computer is the dependent variable which is obtained due to the position of the router which is the independent variable. The distance from the wall, the number of walls between the router and computer and the number of devices on the router all are the examples of the independent variable.  

28. evolution

29. environment, survive, offspring  

explanation:

your answer is, orbit around the nucleus