Let us start by listing the characteristics of the quadratic function in the graph.
With this information, we can exclude some functions.
The second degree curve has an absolute minimum which means that the coefficient in front of x2-term must be positive. Therefore, we can exclude B.
Because the curve cuts the positive part of the y-axis the constant term also has to be positive, which means that you can exclude the function C which has the constant -6.
The only function left is function A.