2 and 3 condition ,would
If the item you purchased had been damaged,you [ would have opted ] to return it to a nearby store for exchange.
i don't know why [ would have opted ]? why p.p?

Question

2 and 3 condition ,would
If the item you purchased had been damaged,you [ would have opted ] to return it to a nearby store for exchange.
i don't know why  [ would have opted ]? why p.p?

Answer

would have opted 意思是 你會已經有選項 這是假設用法
If the item you purchased had been damaged,you [ would have opted ] to return it to a nearby store for exchange.
假如這個物品你買的過去已經損壞 那你就已經有選項退還給附近的商店或換別的商品
注意 你是假設 那商品買之前就已經損壞 所以你就當然會已經有選擇權去換商品 所以用已經完成式

Answer

The "if ... had been damaged" expresses a hypothetical past condition.  The "would have opted" expresses a hypothetical past consequence.

https://www.ef.com/english-resources/english-grammar/conditional/