单选题(共1题,100分) 1、When the low carbon steel specimen is stretched to yield, _______ is correct in the following conclusions.(关于低碳钢试样拉伸至屈服时,以下结论中,_______是正确的。)

A. The stress and plastic deformation increase rapidly, so the material is considered to have failed;(应力和塑性变形很快增加,因而认为材料失效;)
B. Although the stress and plastic deformation increase rapidly, it does not mean that the material has failed;(应力和塑性变形虽然很快增加,但不意味着材料失效;)
C. The stress does not increase, but the plastic deformation increases quickly; therefore, the material is considered to have failed; (应力不增加,塑性变形很快增加,因而认为材料失效;)
D. The stress does not increase, and the plastic deformation increases quickly, but it does not mean that the material fails. (应力不增加,塑性变形很快增加,但不意味着材料失效。)