The correct answer is - d. Arthropoda.
The arthropods are one of the oldest living groups of animals on the planet. Part of this large phylum of animals are the insects, spiders, scorpions, crustaceans. They all have their own unique traits of course, but they also have some that are the same, thus we can say that all the members of this phylum have certain shared characteristics that define them from the other animals.
Some of these shared characteristics are:
- segmented bodies; the bodies are segmented both internally and externally, with some having few segments while some a very large number.
- exoskeleton; they are invertebrates, so they do not have internal bone structure, instead they have external bone structure.
- open circulatory system; the blood is pumped through open spaces called sinuses in order to reach tissues, they lack veins and arteries.
- jointed appendages; all of the extremities are attached to the exoskeleton, enabling them greater flexibility and mobility.
- bilateral symmetry; if an arthropod is vertically cut in half it will be a mirror image as both sides are perfect copies of one another.
