Q: Fact 1: Animals require water for survival.  Fact 2: Hydrogen and oxygen create water.  Given the two facts above, which are required for animal survival?

Available choices:
 (1). hydrogen and oxygen;
 (2). Chemical energy;
 (3). oxygen and methane;
 (4). critical organs;
 (5). sense organs;
 (6). hydrogen and helium;
 (7). light and dark;
 (8). Organic compounds;
A:
(1).