The correct option is
A Monobasic acid & weak lewis acid
Ortho boric acid is a weak Lewis acid as it is electron deficient. It is a weak Lewis acid because of back-bonding from the oxygens attached to the central boron atom. It is monobasic as it reacts with water as,
![](https://search-static.byjusweb.com/question-images/byjus/infinitestudent-images/ckeditor_assets/pictures/9247/content_capture1.png)
Therefore, it is a monobasic acid.