Asked by GIANSH GUPTA KHUNDKER · BIRLA BRAINIACS
Answer: B. too
Answer: (B) too
Explanation: The adverb "too" implies an excessive amount or degree that leads to a negative result, and it pairs structurally with the infinitive phrase "to solve" (too + adjective + to-infinitive). "So" would require a "that" clause later in the sentence (so difficult that...).
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