i think it is D, she has already constructed the hypothesis and needs is performing the experiment. there is not much of an observation stage because she is looking at a distant end result in a set time frame.
The parents are of genotype heterozygous dominant and homozygous recessive. Supposing the dominant allele is N and the recessive allele is n, one of the parents will be Nn while the other nn. The phenotypic (based on visible characteristics) ratio will be 1:1 for dom/rec and rec/rec
In a mammalian brain, there are four major lobes that are present and one of them is the frontal lobe.
The frontal lobe is mainly rich in dopaminergic neurons and thus, it is mainly concerned with functions such as memory, reward, motivation, planning, attention, etc.
The process of break down of tissues and cell death in the tissues is referred to as atrophy and since the frontal lobe is associated with the functions as mentioned above its atrophy would lead to a slow decline in these functions.
Since Mr. Klondlike behavior is changing his blunt comments are most likely a result of atrophy of the frontal lobe.
