He had been sitting in the car for a while waiting for us and listening to the radio . When he went to start his car the battery was dead . So we decided to take my car over there instead . I always hate having to park the car somewhere because then I have to worry is someone going to notice it or is it going to get towed or whatever .

Question: What may be the reason the battery was dead ?
Answer: They forgot to turn on the engine and the radio drained the battery .They just bought the battery brand new but forgot to plug it in .None of the above choices .The weather was cold outside and they forgot to remove the battery .