The correct option is B a few of / many
Before choosing the options, let us understand the difference between "few" and "a few". "Few" means a very less amount, in other words it means "hardly any" or "not many". "A Few" or the other hand means "some", it is usually a little more than "few". "A few" on "the Few" and "few" is mainly used for countable nouns and since in this case, the noun is countable, we would be using "few" or "a few". In this sentence, the first blank specifies to an amount greater than "few" but less than "many". Option B is the correct answer.