Ladder like nervous system is characteristic of which phylum.a) Annelidab) Platyhelminthesc) Molluscad) Chordata

The correct answer is (a) Annelida.

Annelids, which include earthworms and leeches, have a ladder-like nervous system. This type of nervous system is also known as a "ventral nerve cord" or "double ventral nerve cord." It consists of a pair of parallel nerve cords running along the ventral (underside) part of the body. These nerve cords are connected by transverse nerves or ganglia at regular intervals, giving the appearance of a ladder.

Platyhelminthes (flatworms) have a centralized nervous system with a pair of nerve cords, but they do not exhibit the ladder-like arrangement. Mollusca (mollusks) and Chordata (chordates) have more complex nervous systems that are not ladder-like in structure.