Answer: <u>Both parents are heterozygous carriers</u>.
Explanation: Since sickle cell disease is a recessive trait, it means the affected person will have "homozygous recessive" state of genotype only. Here parents are normal, which means they are carriers. So their genotype would be Ss, heterozygous.
Heterozygous parents only will have 25% chances of having their children affected.
Option 1 is incorrect, because if one parent has two recessive alleles, it means he/she is affected and this contradicts the situation mentioned in question.
Option 3 and 4 are incorrect because it is mentioned in question that both parents are normal.
Your answer would be A. The earth element stays in the same area of the lithosphere, hydrosphere, or atmosphere where they originated when the earth was formed.
Answer:
Reproduction without the male
I don't like using W instead we can try to use R 'kay?
R - Dominant
r - Recessive
75% chance that they will have widows peakline children. 25% chance for straight hairline
the answer is (run an experiment) if she wants to prove her hypothesis she has to run experiments