After the new technique was applied to production, the factory has produced ______ over the same period last year.

A．many cars twice as

B．twice as many as cars

C．twice cars as many as

D．twice as many cars as

山区地方性甲状腺肿患病率高，饮水中碘含量低；而平原地方性甲状腺肿患病率低，饮水中碘含量高，由此推断，饮水缺碘与地方性甲状腺肿有关。这种病因推断方法属于：（）。

A、求同法

B、求异法

C、共变法

D、类推法

E、以上都不是