1) He is opposed to tbe idea of hunting humans
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In the passage is says ""But you can't mean_" Gasped Rainsford." He's surprised that General Zaroff actually intents to hunt humans.
Good luck,
he does not always comes up with a complaint
Actually, yes, this is true. Let's look at some examples with the word "all" to see if it agrees with verbs in singular or in plural:
All is lost
All is well
All is arranged already.
All of it is nice
This shows us that "all" agrees with verbs in singular form: the correct answer is a) True.