Option A [tex][x+5=20][/tex]tells us that: When we add 5 to a variable x, we get 20. As it has a unique value for x and is completely equal to it(i.e. 15), It is an equality.
Option B[tex][x=5][/tex] tells us that: A variable x equals to 5. Hence, as x is unique for 5 and is wholly equal to it, it's an equality too.
Option C[tex][x<5][/tex] tells us that: A variable x isn't 5 but lesser than it. As we cannot equate it to 5, nor we are given the nature of the variable x, it is an Inequality.
Option D[tex][x+5][/tex] is an expression; It can't be called an equation or an inequality unless we relate it with another expression.
