The answer you are looking for is the second one. Since the former king was highly liked for his reasonable decisions, you know that the new king must must be doing the opposite of the former king since he is disliked by many. Since he is doing the opposite, arbitrary must be the opposite of reasonable decisions, which makes it an antonym. Hope this helps! Comment if you have questions :)
ok this is how you do it In the chapter “On The Rainy River” in the things we Cary how does Tim O’Brien use various settings to creat a complex meaning