Read the schematic diagram of isobar, where the arrow indicates the wind direction, and answer the question 19-20. The statement about the weather system in A and B is correct () A.

The specific wind direction on the isobar chart is from high pressure to low pressure, with the northern hemisphere deflecting to the right and the southern hemisphere deflecting to the left. The wind in the picture is to the left, located in the southern hemisphere. According to the direction of wind direction, it can be judged that A is the center of high pressure in the southern hemisphere and B is the center of low pressure in the southern hemisphere.

So: BD.