设某商品的需求函数为<img align="middle" alt="" src="/api/uploads/1529630/in-rich-contentcreated_at=1647290108">，则需求弹性<img align="middle" alt="" src="/api/uploads/1529631/in-rich-contentcreated_at=1647290108">（　）.(单选题)
.<img align="\"middle\"" alt="\"\"" src="\"/api/uploads/1529634/in-rich-contentcreated_at=1647290108\"">.,.
<img align="\"middle\"" alt="\"\"" src="\"/api/uploads/1529635/in-rich-contentcreated_at=1647290108\"">.,.
<img align="\"middle\"" alt="\"\"" src="\"/api/uploads/1529632/in-rich-contentcreated_at=1647290108\"">.,.
<img align="\"middle\"" alt="\"\"" src="\"/api/uploads/1529633/in-rich-contentcreated_at=1647290108\"">

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