Answer:
Pia mater
Explanation:
Three meninges cover the brain and spinal cord. Pia mater refers to the deepest meninx of the brain. It is a thin delicate layer of connective tissue. It is a transparent connective tissue layer like that of cellophane. Being a transparent and thin tissue layer, it looks like a cellophane wrap adhered to the surface of the brain.
 
        
             
        
        
        
B. Cell membrane 
Remember cell membrane is the structure aka “wall of the house” is the clear boundary between the cells internal and external environments:)) 
Hope this helps
        
             
        
        
        
The best answer is D.
Hormones are chemical messengers  secreted mostly into blood and also extracellular fluid by specialized tissue of the endocrine system and affect the functioning of other tissues or cells.
Most hormones circulate in blood and come in contact with essentially all cells, but a particular hormone will only affect a limited number of cells, which are termed as target cells to that hormone. 
A target cell responds to a particular  hormone because it bears receptors for that hormone.
For example the red blood cells have receptors for the  hormone called insulin which is produced by the pancreas. The red cells are able to take in glucose  when their receptors bind to insulin. 
 
        
             
        
        
        
A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results. Where possible, theories are tested under controlled conditions in an experiment.
        
             
        
        
        
Answer:No
Explanation:Plants will not just have to rely on one animal to help reproduce. Plants can mimic things such as scents or looks to be an incentive for other animals. Wind and water can also help transport pollen. Plants always have pollinators such as wind, water, insects, and animals. Plants use mimicry in order to attract the biotic pollinators. Plants will never have trouble reproducing because they have so many different pollinators.