Read a schematic diagram of the weather system in a place.

A, fold is because the rock is subjected to horizontal compressive force, causing a series of bending deformation of the rock, including anticline and syncline. According to the bending analysis diagram of rock strata, it is correct because there are only fold structures;

B, according to the stratum analysis in the figure, B is anticline, and at this time B forms a valley, which does not conform to the meaning of the question;

C, according to the strata analysis in the figure, C is syncline. At this time, c forms a mountain, so it does not meet the meaning of the question;

D, according to the stratum analysis in the figure, Ding Bing is syncline. There is no stratigraphic dislocation between the two, so there is no fault, so it does not meet the meaning of the question.

So choose: a.