【正确答案】 1、claimed himself responsible for the explosion    

【答案解析】[解析] 动词claim和短语be responsible for的用法。
[解析] “声称”应译为claim，“对……负责”为be responsible for，二者连在一起时，claimed himself responsible为比较简洁的译法，也可以说claimed (that) he is responsible for...。