表单提交与数据序列化 — 计算机选择题

某页面通过 `fetch` 发送表单数据，代码为 `const fd = new FormData(form); const body = new URLSearchParams(fd); fetch('/submit', {method:'POST', body});`。表单中有两个成功控件：`<input name="tag" value="blue sky">` 与 `<input name="tag" value="R&D">`。请求体的序列化结果是哪一项？ A. `tag=blue+sky&tag=R%26D`　B. `tag=blue%20sky&tag=R%26D`　C. `tag=R%26D&tag=blue+sky`　D. `tag=blue+sky`