Question

Odd man out : Pen-ink , Custard-milk, Reservoir-water, Student-book.

Answer 1

Student book is the odd one so take it out

Mark it brainlist please

Answer 2

 Student-book is the right answer because others such as pen ink, custard milk and reservoir water are available in the liquid form, and student-book is an object.

However, there is a difference between other options such as pen ink, custard milk and reservoir water, and they serve different purposes as well.

But there is no similarity between these options with student-book.