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A variable resistor $R$ is wired into a circuit shown below.

Created for Albert.io. Copyright 2016. All rights reserved.

To what value should this variable resistor be set to generate 0.9A of current passing through the $10\Omega$ resistor?

$\frac{20}{3}\Omega$

$\frac{3}{20}\Omega$

$6\Omega$

$\frac{1}{6}\Omega$

$4\Omega$