Use reasoning to lead to the answer of the following question:
What happens when muscular walls of arteries and veins contract?\nOptions:\n- (A) connection\n- (B) It expands\n- (C) Dehydration\n- (D) construction\n- (E) forces\n- (F) massive damage\n- (G) constriction\n- (H) contraction

(G)
Constriction occurs when the muscular walls of blood vessels contract.

Arteries and veins are blood vessels.

Constriction happens when the muscular walls of arteries and veins contract.

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Final answer: (G)