She cannot be considered intellectually disabled because she must show adaptive problems. The correct option is C.
Intellectual disability diagnosis typically requires the presence of both intellectual and adaptive functioning deficits. In Joan's case, while her IQ score is 65, suggesting intellectual challenges, the absence of signs of adaptive problems means that she doesn't meet the complete criteria for intellectual disability.
Adaptive functioning refers to a person's ability to carry out everyday tasks necessary for self-sufficiency and independence. Options a and b are not accurate because they oversimplify the diagnostic process.
It's not solely about the IQ score, and option d is incorrect as well because having an IQ score that is considered low does not automatically lead to an intellectual disability diagnosis without considering adaptive functioning.