Step 1: Rather than judging all five statements equally, first ask which of them name a technique that does not exist in the standard land grading syllabus, since that quickly flags a false statement.
Step 2: "Plan inspection method" in (A) is not one of the recognised categories, profile, contour adjustment, or plane. Because it is not a real named method, (A) cannot be validated and is rejected.
Step 3: Next, ask whether the plane method, mentioned in (E), is actually rare in field use. Fitting a single sloping plane, or a pair of planes, to a field's elevation data is one of the most commonly taught and applied approaches for reasonably uniform land, so calling it "rarely used" does not match reality, and (E) is rejected too.
Step 4: With (A) and (E) both out, only the choice keeping (B), (C) and (D) remains among the four given, which is option 2.
Step 5: Sanity check the three survivors: the profile method genuinely works by plotting grid-line profiles and overlaying the target grade (B), the contour adjustment method genuinely works by nudging contour lines on the map until cut equals fill (C), and this same contour method is genuinely the natural choice for smoothing flat land destined for irrigation (D). All three are internally consistent with standard land grading theory.\[\boxed{\text{Option 2: (B), (C) and (D) only}}\]