Used until the end of the Second World War,
the German army employed the U-boat to attack both military or civilian watercraft.
A. the German army employed the U-boat to attack both military or
B. the U-boat was employed by the German army to attack both military and
C. the U-boat employed the German army to attack both military or
D. the German army had employed the U-Boat to attack both military and the
E. the U-boat has been employed by the German army to attack both military and also
The grammatically correct sentence is B. "The U-boat was employed by the German army to attack both military and civilian watercraft." The sentence uses the passive voice and correctly employs the preposition “and” instead of “or” to indicate that both military and civilian watercraft were targeted.