A) a common ancestor 
Homologous structures are structures that are similar in related organisms. There is a basic pattern of bones which can be inherited from a common ancestor
        
             
        
        
        
The category is just called plants
 
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Answer:
15 chromosomes
Explanation:
The endosperm is formed through double fertilization where one male gamete nucleus with polar nuclei to form a triploid nucleus called the primary endosperm. The endosperm therefore will contain 15 chromosomes since the polar nuclei is diploid and the male gamete is haploid forming a triploid nucleus.