Primates are an incredibly diverse group of living species between 190 and 350 based on various taxonomic structures and show a broad variety of characteristics that help differentiate them from other mammals.
The hands ofprimates are particularly sensitive and contribute to the sense of contact. Relative to other mammals, the brain areas that deal with eye-hand coordination and stereoscopic are very good and vision are especially large.
The smell characteristics decreases to survive for animals which develop a dependence on other senses, such as hearing or sight.
Hence the correct option is c. enhanced sense of smell.
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.
