Answer:
Option B, Rr pp × rr Pp
Explanation:
Given 
Walnut Comb is produces when  one dominant allele R is present at one gene locus and at least one dominant allele P is present at a second gene locus - R* P*
Rose Comb - at least one dominant allele is present at the first locus and two recessive alleles are present at the second locus - R* pp
Pea comb - two recessive alleles are present at the first locus and at least one dominant allele is present at the second  - rr P*
Single comb - two recessive alleles are present at the first and the second locus  - rrpp
Parent are rose combed and pea combed
For being rose genotype must be R* pp 
and for being pea combed genotype must be rr P*
Rr pp x rr Pp
will  produce 
Walnut comb  with genotype Rr Pp
Single comb  with genotype rrpp
and pea comb  with genotype rrPp
Hence, option B is correct
 
        
                    
             
        
        
        
Answer : In radioactive decay, the half-life is the length of time after which there is a 50% chance that an atom will have undergone nuclear decay. It varies depending on the atom type and isotope, and is usually determined experimentally.
hope it will help you
 
        
             
        
        
        
Popliteus muscle
from: https://en.m.wikipedia.org/wiki/Popliteus_muscle