The answer is b. knowledge
This situation reflects what the text refers to as "filial responsibility".
Filial responsibility is defined as an obligation owed by a grown-up tyke for his parents' necessities of life. Many states have laws that can make grown-up kids fiscally in charge of their parents' necessities of life when the guardians don't have the way to pay for such necessities all alone. The degree of this duty can fluctuate by state.These laws are alluded to as "filial responsibility" laws.
Gravity is a force that exists between any two masses in the universe.
