Answer:
D.) both a and c
Explanation:
Past observations made early in history as well as telescopes and space probes are very important in studying our universe and galaxies. 
- Space probes are increasingly gaining momentum as technological and scientific advancements are being made. 
- Telescopes are used to see or picture objects that are very far away in space. 
- Also, understanding the past records and historical data is essential for the study of the universe. 
Microscopes are not used in galactic studies. They are only used to study the world of micro-organisms. 
 
        
             
        
        
        
Answer:
hydrosphere and biosphere 
Explanation:
The spheres of the Earth are lithosphere, biosphere, atmosphere, hydrosphere etc. Hydrosphere refers to the collection of all the water bodies on the surface of the Earth e.g oceans, lakes, rivers etc. On the other hand, biosphere refers to the collection of life on Earth e.g plants, animals, microbes etc. 
In this question, Water availability is said to impact plant growth and the animals who depend on plants for food. These water availability and the living organisms (plants and animals) it impacts are interactions between the HYDROSPHERE AND BIOSPHERE.
 
        
             
        
        
        
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</span>Most cells of the body have self markers on the surface of their cell called the major histocompatibility complex (MHC). The MHC allows cells of the immune system to recognize the cell as part of our self.<span>system to recognize the cell as part of ourself.</span>