Joe is 24 years old, lives in a rural area, and works as a helper/stock boy in a small local store. Joe's IQ was tested when he was in elementary school and again in high school. His IQ score was about 68 and he did not finish high school. Joe lives in a guesthouse on his parents' farm, and although he does spend lots of time with his family, he takes care of himself.
1. Based on the information provided, Joe should receive a diagnosis of ___________.