The technical term computer <em>crash</em> means that the computer suddenly stopped operating, and the corresponding word from the options is <em>malfunction</em> ( for a system or machine that stops working normaly).
A.<em> reaction </em>: response; repercussion
B. <em>improvement</em> : advance; progress; betterment
C. <em>recovery </em>: the process of having something back; retrieval