Verified answer

如果沒有給一些國家的選項，我們不能，也不會用Which來問，正確的問法是：

What country was this product made in?

正式的英文文法不習慣法介系詞放句尾，所以你也可以講：

In what country was this product made?

專業用語 : What is the origin of this product ?

Which country made this product?

This product was made from that coumtry.

這產品製造來自那個國家 ==>

Which country was this product made in?

這產品製造來自那個國家

This product was made from which country ?

This product is made from that country ?