Answer:
The primary distinction between these two types of organisms is that eukaryotic cells have a membrane-bound nucleus and prokaryotic cells do not.
Prokaryotic Cell
Unicellular
Lysosomes and Peroxisomes absent
Microtubules absent
Endoplasmic reticulum absent
eukaryotic Cell 
Multicellular
Lysosomes and Peroxisomes present
Microtubules present
Endoplasmic reticulum present
 
        
             
        
        
        
Answer:
B
Explanation:
It couldn't be A because meiosis for a spermatocyte results in only 2 male gametes, and it couldn't be C because asexual reproduction is mitosis only
 
        
             
        
        
        
Answer:
The correct answer is option - C. They replaced carbon dioxide with oxygen in the atmosphere.
Explanation:
Cyanobacteria or Blue-green algae is a group of bacteria that is making its own food using water and carbon dioxide in the presence of sunlight, the process of photosynthesis
These organisms release oxygen as a byproduct of photosynthesis in the atmosphere. Through this process, these organisms replaced carbon dioxide with oxygen in the atmosphere in the early earth.
Thus, the correct answer is option C. They replaced carbon dioxide with oxygen in the atmosphere.