Answer:
While doing medical research on the human subject, following limitations are unavoidable:
a). Privacy: The privacy of the subject involved in the research should be maintained.
b). the subject must be allowed to the minimal exposure to risks and it must be tested on animals first to avoid deaths.
c). The risk associated with the physiological and physical well being of the subject must be considered.
d). The subject must be well instructed about all the risk and procedure involved in the research.
It is either <span>Igneous rock or </span><span>Sedimentary rock. But if I were to choose one, I would choose Igneous.</span>
Answer: B. Water breaks down into oxygen molecules for respiration.
Water is the required for photosynthesis, a process by which plants (terrestrial and aquatic) makes their food by utilizing water as a reactant to produce oxygen and glucose as product. The glucose act as a source of energy for conducting various metabolic processes in plants but oxygen is released in the air.

This oxygen is necessary for terrestrial and aquatic animals for respiration. Therefore, water breaks down into oxygen by the process of photosynthesis, hence water plays important role in respiration in living beings.
Mitosis is the process by which the nucleus of a cell divides to form two new nuclei?
<span>Carbon is the only element that can form many different compounds. Each carbon atom can form four chemical bonds to other atoms. This allows it to form rings and chains.</span>