The barnacles are only able to attach them selfs to surfaces in the water. Since the surface is limited, barnacles are attaching themselves to the other barnacles, crowding the rock. The muscles were not able to grow or attach themselves off the surface of the rock. Same thing with the mussels that are growing on the rock. So not only barnacles are crowding the rock, but Mussels as well are crowding the rock.
 
        
             
        
        
        
Answer: D. 100%
Explanation:
One parent is with is a true breeding blue flowering plants this means the two alleles of the genotype are homozygous dominant alleles (BB).
The other parent is a true breeding with flowering plant, this means the two alleles of the genotype are homozygous recessive alleles (BB).
When both parents are crossed, the possible genotype outcome is 
B B  *  b b
Bb Bb Bb Bb
Therefore since the blue flowering plant allele (B) is dominant to the white flowering plant allele (b) the probability of an offspring outcome to be a blue flowering plant is 4/4 which is 100%.44
Answer is 100%
 
        
                    
             
        
        
        
Heyy there. 
I'm thinking that it would be B. or D. but idk exactly which one it is.
I hope you figure out wat it is.
B. Thinnest under the oceans and thickest under continents 
D. Least dense layer overall, consists of two layers of different thickness
Good Luck and enjoy the rest of ur day!! ^^