Error spotting (conditional inversion vs. past counterfactual): Identify the erroneous segment (A/B/C) — choose D if there is no error — 'Were he / to see you, / he would have been surprised. / No error.' Ensure correct time reference between the 'if'-clause and the result.

Concept/Approach: Matching conditional forms
'Were he to see you' (inverted form of 'If he were to see you') describes a hypothetical present/future condition. Its natural result is 'he would be surprised'. Here the result is past counterfactual ('would have been surprised'), which requires a past-unreal condition: 'Had he seen you' or 'If he had seen you'.

Step-by-step correction
Make the condition past unreal to match the result: (A) 'Were he' → 'Had he'.Corrected sentence: 'Had he seen you, he would have been surprised.'

Alternative fix
Keep (A) but change the result to present: 'Were he to see you, he would be surprised.'

Final Answer
(A) is erroneous in this pairing → use 'Had he …' for a past-unreal condition.