Which combination of variables will make an experiment the most reliable? A. One dependent variable and one experimental variable
B. One controlled variable and many experimental variables
C. Two controlled variables
D. Two experimental variables

**urgent** roberto plans to use two transformers to reduce a voltage of 120 v to 4 v. he uses a transformer that has 300 coils in the primary winding and 50 coils in the secondary winding. he has four other transformers, as listed in the table. which transformer should roberto use to have an ending voltage of 4 v? a- w b-xc- yd- z