For example, "isothermal surface (the surface formed by isothermal point) and isobaric surface in a certain area of China on a certain day". Reading questions 3-5. In this weather system,

According to the analysis of the middle temperature surface in the figure, A is located above isothermal surface and B is located below isothermal surface, indicating that A's temperature is lower than B's; according to the analysis of the middle pressure surface in the figure, B's isobaric surface arches upward, indicating that B is a high pressure area, and B's temperature and pressure are higher than A's, and it is subtropical high in summer and dry weather. Controlled by subtropical high, it is characterized by hot and dry weather.

So choose: a.