What major behavior changes in dogs have occurred as a result of increased dependency on humans?
a. reduced predation and problem-solving abilities
b. decreased urine marking and barking
c. increased tendency to roam and show aggression towards
other dogs
d. increased fear and wariness toward strangers

Animal companionship refers to the people owning animals. There are several reason why people decide to own animals, or pets.They give but also receive love and affection from their animals.
Because of these owners' interactions  and the increased dependency on humans  several behavior changes in dogs occured. The major behavior changes are:
A. Reduced predation and problem-solving abilities.
The reason is simple: Dogs get used to the attention, support and care of the humans, so as the time pasts they lose the ability to solve problems on their own.