Which of the following statements is true about water on earth compared to other planets in the solar system?

earth is the only planet that has any water at all.

earth is the only planet that has water in all three phases: solid, liquid, gas.

earth is the only planet that has gaseous water.

earth is the only planet that gets cold enough to produce solid water, or ice.

the electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, x-rays, and gamma-rays.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.