4. Perhaps the most significant postwar trend was the
decentralization of cities throughout the United States,
_________ when massive highway-building programs
permitted greater suburban growth.
A. and accel erated a phenomenon
B. a phenomenon that accelerated
C. accelerating a phenomenon which,
D. the acceleration of which phenomenon
答案是B 但是我想請問題目的第2句 是否有缺動詞?
這樣選B沒錯嗎?
謝謝大家