The attack in which the attacker sends a fragmented message that the victim cannot reconstruct is a(n) attack.

A teardrop attack

Explanation:

A teardrop attack also  called  denial-of-service  attack is one  which an attacker, usually a hacker  sends many  fragmented bug data messages  to a victim's machine causing a crash in the device. This is because data moves in small data packets of whose transmission should follow layers according to the model of the devise be it OSI or  TCP/IP model. Now when a hacker continually sends huge amounts of packets of bug data, the process of data transmission fails and  packet data becomes overlapped, making the victim 's device machine in disarray and difficult to reconstruct while trying to  rearrange them. When the hacker continually sends in more bug data packets to the already confused machine,  The machine system crashes.