The correct option is A 2x - 3 = 0
We know, an equation is a statement that asserts the quality of two expressions, which are connected by the equal sign.
The first option is x + 4.
This is an expression, since it does not contain the equal sign.
The second option is 3x - 9
This is also an expression, since it does not contain the equal sign.
The last option is 2x - 3 =0
This has expressions on LHS and RHS connected by equal sign. Hence, this is an equation.
So, in the given list, 2x - 3 = 0 will be an algebraic eqaution.