TRAP routines need to be able to return to the instruction after the TRAPinitiation. The location of this instruction will differ between TRAP instances, andcould be anywhere. The RET instruction solves this problem by using the addressstored in R7, which is the next PC address that was saved when the TRAP occurred.The BR instruction will always jump to the same PC-relative address, which cannotwork in the general case. Also note that the RET instruction is base + offset and theBR instruction is PC-relative, so the BR instruction might have insufficient reach(partial credit answer).