nopCommerce product comments plugin allows user to comments on the product. You just need to install the nopCommerce product comments plugin and it will start showing the comment box in product details page.
The user can easily ask the comment question and admin can also reply the comment questions.
It is easy to install and configure the plugin and you are good to go ahead to use it in your nopCommerce Store. It support nopCommerce 4.0 version.