The rock was weathered by water, sand, and other rocks
B - it suggests that parent's words were held in very high regard
The father had high aspirations for his son and told him what to do - the son willingly followed his father's directions, knowing that he was wise and only wanted what was best.
If I understand the question right I would believe it to be 5 miles an hour because the course is a mile and he ran a mile in 12 minutes. We know an hour is 60 minutes so we have to divide the number of minutes he is talking from the hour. 60 divided by 12 is 5 so if he is running a mile every 12 minutes then he is running 5mph