低碳钢的拉伸应力-应变曲线应为下列哪一种？【2009-57】

• A.<img src="https://timg.fentiku.com/101/2016/10/21/L4bQPt3vy9.png" title='L4bQPt3vy9.png' alt='L4bQPt3vy9.png'/>
• B.<img src="https://timg.fentiku.com/101/2016/10/21/tz7T5gNnui.png" title='tz7T5gNnui.png' alt='tz7T5gNnui.png'/>
• C.<img src="https://timg.fentiku.com/101/2016/10/21/9rzuptLVMG.png" title='9rzuptLVMG.png' alt='9rzuptLVMG.png'/>
• D.<img src="https://timg.fentiku.com/101/2016/10/21/lLAYkbb7Mw.png" title='lLAYkbb7Mw.png' alt='lLAYkbb7Mw.png'/>

正确答案：A