Assertion [A] : Platyhelminthes are acoelomates.
Reason [R] : In platyhelminthes the coelom is filled with a packing tissue called mesenchyme.
Assertion [A] and Reason [R] are True.
In platyhelminthes the coelom is filled a packing tissue called mesenchyme. So there is no space available for the formation of coelom as a result they are acoelomates. This feature is also an adaptation for their parasitic mode of nutrition.