The correct answer is: We can hardly believe that the situation is so serious as to justify such precautions as you have taken.
The word “hardly” is an adverb that means “almost not.” In this sentence, it is used to modify the verb “believe.” The sentence means that we find it almost impossible to believe that the situation is so serious.
The word “as” is a conjunction that can be used to compare two things. In this sentence, it is used to compare the seriousness of the situation to the level of precautions that have been taken. The sentence means that we believe that the precautions that have been taken are justified by the seriousness of the situation.
The word “to” is a preposition that can be used to indicate a purpose or goal. In this sentence, it is used to indicate the purpose of the precautions that have been taken. The sentence means that the precautions have been taken in order to address the seriousness of the situation.
The word “such” is an adjective that can be used to refer to a particular thing or group of things. In this sentence, it is used to refer to the precautions that have been taken. The sentence means that we believe that the precautions that have been taken are appropriate for the seriousness of the situation.
The word “as” is a conjunction that can be used to introduce a clause that provides additional information. In this sentence, it is used to introduce a clause that describes the precautions that have been taken. The sentence means that we believe that the precautions that have been taken are appropriate for the seriousness of the situation.