"in other than dwelling units, gfci protection shall be provided for all 15a and 20a, 125v, single" phase receptacles installed within ft from the top inside edge of the bowl of a sink:
(a) 3
(b) 4
(c) 5
(d) 6

(d) 6                

Explanation:

           The GFCI stands for the "Ground fault circuit interrupter". It protect the house or units form short circuits. It is a kind of circuit breaker which disconnects or breaks the electric power when it finds any imbalance between the incoming current and the outgoing current.

            The ground fault circuit interrupter protects the receptacles from being overheating and catching fires. The GFCI are installed with 6 feet from the top of the sink.

Thus the answer is --

(d) 6

explanation:

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