It was now clear that no such weapons were manufactured and none been found .

【正确答案】 A

【答案解析】解析：时态应用。“and”连接的两部分是并列关系，时态应一致，因而排除C、D。found是find的过去式，表“发现”；founded是found的过去式，表“建立，创立”，根据题干意思，本题应选A。