Question

to separate a mixture of hard candies and marbles, the most efficient method would be passing the mixture through a filter sorting the mixture by hand adding water to the mixture

Explanation:

To separate hard candies and marbles:

• "Passing through a filter" won’t work as both are solid and likely similar in size to pass through or be retained (no liquid involved).
• "Adding water" is irrelevant as neither dissolves (candies might be hard, not dissolving quickly, and marbles are insoluble).
• "Sorting by hand" is efficient here—they are distinct solids (different appearance/feel), so manual sorting is practical.

Answer:

sorting the mixture by hand