What is the author's claim in this passage?
adapted from Submarines
from The Story of Great Inventions
by Elmer Ellsworth Burns
ary Test
Successful navigation beneath the surface of the water, though not carried to
the extent imagined by Jules Verne, was a reality at the beginning of the
twentieth century. Instead of twenty thousand leagues under the sea, less
than a hundred leagues had been accomplished, but no one can foretell what
the future may have in store.
The submarine is primarily utilized in wars. The weapon used by the
submarine is the torpedo. The torpedo is itself a small subma ne able to
propel itself, and if started in the water toward a certain object, to go under
water straight to the mark. It carries a heavy charge, either of guncotton or
dynamite, which explodes when the torpedo strikes a solid object, such as a
battle-ship.
It would be very difficult for one submarine to fight another submarine, for the
submarine when completely submerged is blind. It could not see in the water
to find its enemy. The torpedo-boat-destroyer is able to destroy a submarine
by torpedoes, shells full of high explosives, or quick-firing guns. Advantage
must be taken of the moment when the submarine comes to the surface to
get a view of her enemy.
A It is difficult to destroy a submarine.
OB. Submarines are able to successfully navigate under water.
C. It is difficult for submarines to fight against each other.
OD. Submarines are mostly used in warfare.