Which of the following is generally considered the most frequent technical error leading to failure of an arthroscopic anterior cruciate ligament (ACL) reconstruction?

Explanation:
The correct option is a. Non-anatomic tunnel placement, particularly placing the femoral tunnel too anteriorly or vertically, is historically the most common technical error leading to altered knee kinematics, recurrent instability, and subsequent graft failure in ACL reconstruction. Reference: Harner CD et al., Am J Sports Med.