The correct answer is C. Tissue
Explanation:
In the diagram, x is between organ and cell level. This implies this level of organization is smaller than an organ but no as small as one cell. In this context, the most suitable term to add to this level is a tissue because these are structures composed of specialized cells, which shows this level encloses cells. Also, a group of tissues forms an organ; this implies the organ is the level that follows the tissue. Examples of this include muscle tissue composed of muscle cells and that is part of organs including the heart.
Because the stomach is lined by a mucous membrane (the gastric mucosa)
The controlled experiments are performed by the scientists, when they want to study the changes in the sample on changing a single variable. So, the correct answer is option (b).
In case, all variables are kept same, no changes would be observed in the experiment sample. A controlled experiment can be performed on living thing as well as non living. But, controlled experiment cannot be performed on the things which are influenced by a lot of variables, as they cannot create realistic results. So, the option (a), (c), and (d) are incorrect.
Answer: The Organism is most likely to be a starfish