8. r_x is normally ________. a a variable resistor b a known precision resistor c an unknown precision…

Brief Explanations:

In electrical circuits, $R_X$ is often used to represent an unknown - value resistor. It is the resistor whose resistance value we are trying to determine or measure. The other resistors in the circuit (like $R_1$, $R_2$, and $R_s$) may have known values or be used for calibration or comparison purposes, but $R_X$ itself is of unknown value.

Answer:

d. an unknown value