Final answer:
To separate a mixture of fine salt, sand, and small pebbles, both filtration and evaporation techniques should be employed; filtration to remove the sand and evaporation to separate the salt from the pebbles. Option number 1 correct.
Step-by-step explanation:
The separation of fine salt, sand, and small pebbles can be accomplished using physical methods of separation. The first step might be filtration, which would allow for the separation of sand from salt and pebbles since sand would be retained on the filter paper. However, filtration alone may not be sufficient for separating salt and pebbles, as these could pass through together.
Evaporation can be used to separate the salt by dissolving it in water and then evaporating the water, leaving behind the salt crystals. Since pebbles would not dissolve, they would be left behind. Magnetic separation is irrelevant here as none of the substances are magnetic. Therefore, the correct answer to the student's question is a combination of both filtration and evaporation.