设某商品的需求函数为<img align="middle" alt="" src="/api/uploads/60000061731/in-rich-contentcreated_at=1648696590">，则需求弹性<img align="middle" alt="" src="/api/uploads/60000061732/in-rich-contentcreated_at=1648696590">（　）.(单选题)
.<img align="middle" alt="" src="/api/uploads/60000061733/in-rich-contentcreated_at=1648696590">
.<img align="middle" alt="" src="/api/uploads/60000061734/in-rich-contentcreated_at=1648696590">
.<img align="middle" alt="" src="/api/uploads/60000061735/in-rich-contentcreated_at=1648696590">
.<img align="middle" alt="" src="/api/uploads/60000061736/in-rich-contentcreated_at=1648696590">

---