Pioneer species are the first species to arrive in an area after succession (hope this helped because i dont know about climax communities)
The suggestion is to prevent a puddle of the liquid present in the sample from forming or from it leaking on to the surface on which it is placed. For example, if precipitates of a solid are removed from water and then placed on filter paper to dry, the water will soak into the filter paper and then leak on to the counter on which it is placed. If this precipitate were placed in a watch glass or weighing paper, the water would only evaporate and would not contaminate the sample.
The first step in the two-step process of making a solution is the breakdown of the solute source into Atomic particles
for a solution to break the solute must be dissociated and break into the atomic particles
so correct option is D
hope it helps