There is no need to worry too much. In fact we shall solve this problem ________ law and education. [ ]

A. by means of

B. in terms of

C. in case of

D. in control of

安全仪表中可燃气体报警器、毒气报警器的检定周期为（）个月；火灾报警系统的检定周期为12个月。