题目选项分析

Whereas both Europe and China use standard railroad gauge (1435 mm), Russia deliberately chose the wider "Russian gauge" (1520 mm) that gives greater side-to-side stability in railways cars and, more importantly, acting as a national defense, blocking a foreign army's supply line and preventing these bordering powers from invading by train.

Whereas both Europe and China use standard railroad gauge (1435 mm), Russia deliberately chose the wider "Russian gauge" (1520 mm) that gives greater side-to-side stability in railways cars and, more importantly, acts as a national defense, blocking a foreign army's supply line and preventing these bordering powers from invading by train.