Although the actual questions are missing from your ask, here's how you can tell.
If the study will be messed up (added bias) through interaction with the subjects the study should be observational. For example if a biologists wanted to study the eating habits of wild birds in the tropics, they would need to do an observational study. if they did a controlled experiment, the birds will change their eating habits based on human interaction, thus making the study invalid.
If the study requires specific measurements, close monitoring, or contact and interaction with the subjects the study should be a controlled experiment. For example, if a scientist wanted to test out a new drug, the health of patients would need to be closely monitored.
Answer: b) skraplanie
Explanation:
As part of the hydrological cycle, water is evaporated off of the surface of the earth and turns into the gaseous form of water which is water vapor. With temperatures getting colder as you go higher, the water vapor will begin to condense into water droplets in the process called Condensation.
As this happens, the water droplets will come together and begin to form clouds. This will continue till the cloud gets too heavy for the capacity of the atmosphere and will then fall as rain.
The answer is 26,679,999,999,996
<em> DNA replication needs to occur because existing cells divide to produce new cells.Each cell needs a full instruction manual to operate properly. So the DNA needs to be copied before cell division so that each new cell receives a full set of instructions!</em>
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<em>HOPE</em><em> </em><em>IT</em><em> </em><em>HELPS</em><em> </em><em>YOU</em><em> </em><em>OUT</em><em> </em><em>PLEASE</em><em> </em><em>MARK</em><em> </em><em>IT</em><em> </em><em>AS</em><em> </em><em>BRAINLIEST</em><em> </em><em>AND</em><em> </em><em>FOLLOW</em><em> </em><em>ME</em><em> </em><em>PROMISE</em><em> </em><em>YOU</em><em> </em><em>TO</em><em> </em><em>FOLLOW</em><em> </em><em>BACK</em><em> </em><em>ON</em><em> </em><em>BRAINLY.IN</em></h2>
Answer:
Microglial cells
Explanation:
Microglial cells are one of the various types of neuroglial cells in the central nervous system. Microglial cells are the small cells and have thin slender processes. Many spine-shaped outgrowths come out of these processes. Microglial cells serve as phagocytes of the central nervous system. These cells clean the cellular debris that is generated during the normal development of the nervous system. Microglial cells also perform phagocytosis of microbes and damaged nervous tissue.
