The correct answer is: E. No error
The sentence is grammatically correct. The subject and verb agree, and the sentence is complete.
Option A: “All of you will agree with me” is a complete sentence.
Option B: “that no problem faced by our society” is a subordinate clause that modifies the verb “agree.”
Option C: “is as grave and intractable” is a comparative clause that compares the problem to other problems faced by society.
Option D: “as this problem is” is a relative clause that modifies the noun “problem.”
The sentence is a complex sentence with two independent clauses and one subordinate clause. The independent clauses are “All of you will agree with me” and “no problem faced by our society is as grave and intractable as this problem is.” The subordinate clause is “that no problem faced by our society is as grave and intractable.”
The sentence is grammatically correct and makes sense.