GPIOA.0接一开关,开关另一端接地,GPIO.1通过1k电阻接一LED,LED另一端接3.3V,要求开关闭合,灯亮,开关断开,灯灭。则初始化代码为: A. GPIOA->PUPDR|=1<<0;GPIOA-> MODER |=1<<2; GPIOA_OTYPER=1<<1; B. GPIOA->PUPDR|=1<<0;GPIOA-> MODER |=1<<2; C. GPIOA-> MODER |=1<<2; GPIOA_OTYPER=1<<1; D. GPIOA->PUPDR|=1<<0; GPIOA_OTYPER=1<<1;