(A) 条件(1)充分，但条件(2)不充分． (B) 条件(2)充分，但条件(1)

问题：

(A) 条件(1)充分，但条件(2)不充分．
(B) 条件(2)充分，但条件(1)不充分．
(C) 条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．
(D) 条件(1)充分，条件(2)也充分．
(E) 条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．

Automobile A is traveling at two-thirds the speed that Automobile B is traveling. How fast is Automobile A traveling
(1) If both automobiles increased their speed by 10 miles per hour, Automobile A would be traveling at three-quarters the speed that Automobile B would be traveling.
(2) If both automobiles decreased their speed by 10 miles per hour, Automobile A would be traveling at half the speed that Automobile B would be traveling.