The circuit diagram below shows the locations of four switches. all four
switches are initially closed. which switch must be opened in order to create
a complete (not short) circuit?

switch 2 must be opened  Answer (C)

Explanation:

If you leave switch 2 closed, there will be a short circuit because the current will go through the path of less resistance, therefore selecting the line where switch 2 is located, and avoiding all other branches where the resistors are placed.

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