Error Detection And Correction

Step 1: Identifying the error.
The error lies in the phrase "discussed about the problem." The verb "discuss" does not require the preposition "about." It should simply be "We discussed the problem."
Step 2: Analyzing the options.
(A) We discussed about the problem so thoroughly: Incorrect. The phrase "discussed about" is grammatically incorrect. The correct phrase is "discussed the problem."
(B) on the eve of the examination: No error here. The phrase is grammatically correct.
(C) that I found it very easy to work it out: No error. This part is correct.
(D) No error: This would be the answer if there were no errors.
Step 3: Conclusion.
The correct answer is (A), as "discussed about the problem" is incorrect. It should simply be "discussed the problem."