[单选题]
The length of time the o*gwy)qx w7b (x4 6hi*.(rigoh8pmymsmjkes5/6 qdolh;j. dh /(lm-ghutter is open and the film is exposed in a camera is determined by5eq; s/jhdl. kg d h/o-6mmj(l the
A. shutter speed.
B. f-stop.
C. focusing.
D. none of the given answers
