I believe the correct answer is B. Nephridia are excretory organs. They are organs found in invertebrate animals that are present in pairs and are responsible for performing functions that are similar to the kidney of a vertebrate. They excrete wastes from metabolic processes.
        
             
        
        
        
C. How can we make an artificial heart
        
             
        
        
        
They are pervasive and play many different roles in the marine environment, from being the base of the food chain, controlling much of the flow of marine energy and nutrients, and being essential to the ocean's health.
 
        
             
        
        
        
Answer:
Phenotypic ratio= 1 Brown : 1 Gray
Explanation:
Genotype of brown snake= BB
genotype of gray snake= Bb
A cross between brown (BB) and gray (Bb) snake obtains progeny in following phenotypic ratio= 1 Brown : 1 Gray
Here, the heterozygous parent, gray snake (Bb) forms two types of gametes in 1:1 ratio while the homozygous dominant parent, brown snake (BB) forms only one type of gamete.