Let us define each property given in the option.
Think about the rules for addition.
Think about commutativity property.
How many sides are there in an octagon? What does regular octagon mean?
Think about the operation.
How many sides are there in a rectangle?Are the length of opposite sides of a rectangle same ?
In the expression , put the value of a.
How many sides are there in a square? Are all of them of same lengths?
How many edges are there in a cube?