The correct options are
B As the proportion of land is comparatively greater in the northern hemisphere, the distance between the isotherm lines varies.
D As the proportion of land in the southern hemisphere is limited, the distance between the isotherm lines is fairly constant.
As the proportion of land is comparatively greater in the northern hemisphere, the distance between the isotherm lines varies. As the proportion of land in the southern hemisphere is limited, the distance between the isotherm lines is fairly constant.