题目2单选题
设B不含变元x,<img src="https://tihai-oss-cloud.itihey.com/img/610aa0f133609713ede4447b2193b4ea.png">等值于____A. <img src="https://tihai-oss-cloud.itihey.com/img/e734dfa134ef1ec0813d18566552cf2f.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/c4f10b32fddc0deb6f01d613f3659d8b.png">C. <img src="https://tihai-oss-cloud.itihey.com/img/70bd5e21b22bc6e854aedbc4dbbec748.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/a2b6c1db3a9ae26085cb3e4d92fceb1c.png">