Option 1 -> The passage states "No one knew he'd taken an unplanned drive out of Victoria, so they'd have no reason to look for him here."
Option 2 -> The passage does not mention anything about Michael having or not having friends.
Option 3 -> There is no indication in the passage that Michael avoided attention; this is not given as a reason.
Option 4 -> The non-working horn is mentioned as a reason he couldn't get drivers' attention, not why people wouldn't search for him.
Hence, Option 1: the trip was unplanned -> Michael specifically thinks no one would look for him because nobody knew he had taken this unplanned drive out of Victoria, so they wouldn't know where to search -> correct