$(a)$ Associate any three phyla of Animalia with triploblastic body organisation and bilateral symmetry.
$(b)$ State the meaning of triploblastic body organisation and bilateral symmetry.
$(c)$ On the basis of presence or absence of coelom,compare the three phyla answered in $(a)$.

(N/A) Organisms belonging to phyla Platyhelminthes,Nematoda,and Annelida are triploblastic and exhibit bilateral symmetry.
$(b)$ Triploblastic body organisation refers to the presence of three germinal layers (ectoderm,mesoderm,and endoderm) in the developing embryo. Bilateral symmetry means that the body can be divided into identical left and right halves along a single plane.
$(c)$ Comparison based on coelom:
$1$. Platyhelminthes: Acoelomatic (lack a body cavity).
$2$. Nematoda: Pseudocoelomatic (have a false body cavity).
$3$. Annelida: Coelomatic (have a true body cavity lined by mesoderm).