to classify it as a protostome, zoologist must see for the mouth development in the embryo.
Explanation:
The protostome are the animals which are unique to their three germ layer in embryonic development, with the bilateral symmetry as they have the ability to fly with other protostome developments.
the one characteristic feature to distinguish them as the protostome, mouth part development is to be sought as the mouth develops but not the anus in the embryo. the mouth parts serves unique to the group and their feeding structures.
The correct answer is - the variable.
With the experiment, in the way that Dan had decided to perform it, the fertilizer is the variable, as in one of the parts with strawberries he uses fertilizer, while in the other part he doesn't uses fertilizer.
While this kind of experiment may give Dan some answers, and he might notice differences, still he would have to be more detailed in the experiment to see for sure if the fertilizer is the thing that makes some of the strawberries grow better than the others.
Dan should also put all of the strawberries at places that would receive the same amount of light, experience the same weather conditions, receive the same amount of water, and to be planted in a soil of the same quality. Only like this, after putting the fertilizer, Dan can now if it makes any changes or not.
Mucous coats and protects the inside of the stomach
Answer: B
Explanation: Researchers have induced differentiating cells to revert to being stem cells. According to Spradling, it has long been known that some specialized, or differentiated, cells in the body can revert to become stem cells to regenerate tissue under particular conditions
