List of top Zoology Questions on Regulation of gene expression

Which of the following statements are correct?
A. In complete dominance of one allele, heterozygous phenotype is same as that of homozygous dominant. 
B. In codominance, both phenotypes are expressed in homozygotes. 
C. In multiple allele cases, genes have more than two alleles in the population. 
D. In pleiotropy, multiple gene affects single phenotypic character. 
Choose the correct answer from the options given below