Answer: Option (A) is the correct answer.
Step-by-step explanation:
Since there are many elements in the periodic table which are grey in color and they are also able to react with water.
For example, silicon, iron, cobalt, nickel, tungsten etc are all grey in color.
Therefore, when we are given an unknown element which is grey in color and reacts with water then we cannot exactly tell which element it is unless some more of its specific properties are given.
Thus, we can conclude that the correct statement will be, not reliable because many metals are gray and several react with water.