Bill is having a hard time making friends. Often, he misses…

Bill is having a hard time making friends. Often, he misses social cues that his peers make, such as continuing an activity after everyone left, or not saying, “hi” back to them when they greet him. He really enjoys cars and trucks and will sometimes discuss it, even when his peers try to talk to him about something else. Which of the following developmental disorder / learning disability is likely affecting Bill?