The biggest difference between Observational studies and Experimental<br/>research is( ) A: Intervention or treatment B: Prospective C: Random allocation D: Paralleled control group E: Blinding

Few went out in such a cutting and blinding wind.______ A: 在如此刺骨的和刮得叫人睁不开眼的风里，很少有人出门。 B: 因为刺骨的风和刮得叫人睁不开眼睛的风，很少有人出门。 C: 很少有人出门，因为这刺骨的和刮得叫人睁不开眼的风。 D: 寒风刺骨，刮得叫人睁不开眼睛。在这样恶劣的天气，很少有人出门。