Use the Information to Answer the Question

Multiple Choice

Use the information to answer the question.
Trichoplax adhaerens is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 µm high, are irregularly shaped, and consist of a total of about 2,000 cells, which are diploid (2n = 12) . There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. Individual animals move using cilia, and any "edge" can lead. T. adhaerens feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. T. adhaerens sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.
Which of the following T. adhaerens traits is different from all other known animals?

A) T. adhaerens is multicellular.
B) T. adhaerens lacks muscle and nerve cells.
C) T. adhaerens has cilia.
D) T. adhaerens lacks cell walls.