Sponges
a) have larvae which are motile and move via the motion of cilia
b) are the simplest diploblastic animals
c) have a nerve net but not a central nervous system
d) have feeding cells called dinoflagellates

Have larvae which are motile and move via the motion of cilia. (Ans. A)

Explanation:

Sponges: They are belongs to porifera phylum and defined as the simplest species. In sponge for particular function they are containing specialized cells, and they lack true tissues. All sponges are marine or aquatic in nature.

Sponge lives in contact with water because it helps them to excretion, gas exchange, and feeding. They can filter out the food, eliminate waste, and absorb dissolved oxygen with the help of body structure of sponge is dedicated to moving water.

Sponges produce motile larvae through the process of sexual reproduction, and move with the motion of cilia or budding formation through the process of asexual reproduction.

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.