I believe it is all of the above. So D.
Answer:
The recessive allele well be masked by the dominant allele in the heterozygous genotype
The connective tissues of mammalian brain is called the meninges. There are three layers of this tissue. The outer layer is called the dura mater. The arachnoid is the middle layer and the pia mater is the inner layer of it.
The right option is; A) gametes
Gametes are reproductive cells (male (sperm) or female (eggs)) that contain only half the usual number of chromosomes and unite during sexual reproduction to produce a new cell (zygote). The mutation for sickle cell anemia occurs in the woman’s gamete (eggs) and this type of mutation is known as germline mutation; a mutation that occur in the germ (reproductive) cells and can be passed on to an organism’s offspring.