Right option is (b) Sectoral antenna
The best I can explain: In Sectoral horn antenna, flaring is done only in one direction. Depending on the flaring direction with respect to field propagation, it is divided into E-plane or H-plane horn antenna. Conical horn flared cross section is in shape of a cone.Pyramidal horn flared cross section is in shape of a four-sided pyramid. In exponential horn, the separation of sides increases as a function of length.