【单选题】
下列等于1的定积分是( )
①
<img src=https://huaweicloudobs.ahjxjy.cn/5FD5E72DE4CB8B5C565B0087A458BED7.png title=)Z5D%]1]@`@FGQOI)BZCX)Y.png alt=)Z5D%]1]@`@FGQOI)BZCX)Y.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/A539715B009F51D05E6CA7DBE9AF3C5C.png title=2PW07ZW5)S60%W@9WZYH7(N.png alt=2PW07ZW5)S60%W@9WZYH7(N.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/261165CC4472BB7F00490803A43460CA.png title=EK7(6J9G@P5APB5}G3U4OZE.png alt=EK7(6J9G@P5APB5}G3U4OZE.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/D5C0B65DF825C90B4AB00802170E6156.png title=RX%H9PYM0`H16ZEP)R{OI}4.png alt=RX%H9PYM0`H16ZEP)R{OI}4.png/>