( ( ( The pathway ) ( taken ( by ( an ( electric current ) ) ) ) ) ( ( is ( a circuit ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN pathway)) (VP (VBN taken) (PP (IN by) (NP (DT an) (JJ electric) (NN current))))) (VP (VBZ is) (NP (DT a) (NN circuit))) (. .)))
The  pathway taken by an electric current is a circuit.
(ROOT (NP (NP (NP (DT A) (JJ parallel) (NN circuit)) (VP (VBZ is) (VP (RBS best) (VBN described) (PP (IN as))))) (: :) (NP (NP (NN electricity) (NNS flows)) (PP (IN along) (NP (QP (JJR more) (IN than) (CD one)) (NN pathway))))))