--Do you know what caused the accident?- No not yet. The matter .A. is being looked in

问题补充：

--Do you know what caused the accident? --- No, not yet. The matter .

A. is being looked into

B. was being looked into

C. looked into

D. is looked into

答案：

(答案→)A. is being looked into

B. was being looked into

C. looked into

D. is looked into

解析：考查时态语态。因为回答是还没有知道，说明这件事情还在调查之中。所以用现在进行时。