The right answer is C. Silt is more vulnerable...
In geology, a silt is a sedimentary formation whose grains are of intermediate size between clays and sands that is to say between 2 and 63 micrometers (the precise limits may vary somewhat according to the laboratories). A mostly silty deposit may be called silt. In geology, Anglicism silt is often used to designate silts.
The silt is the ultimate product of fluvial erosion of the rocks of the river catchment. The silty particles thus consist of very fine debris of quartz, mica and feldspar, or even clay minerals.
Stringers characterize the loess deposits of loess, also known as "slime plateaus", and are common in alluvial deposits. In the latter case, the silty particles release nutrients which have a major interest for the renewal of soil fertility and therefore for their agricultural exploitation.
Since silt is often suspended in water, it can contribute to its turbidity.
