【单选题】

We are interested in the weather because it (21) us so directly-what we wear, (22) we do, and even how we feel. Geographers, however, are (23) interested in climate than in weather.Climate is the pattern of all the weather conditions over a long period of time. Generally (24) , climate (25) to these normal weather conditions, not (26) daily or yearly changes.

Climate, like weather, changes (27) time. It is true (28) these changes (29) a long time, but not as long as we might expect. Records show that over the centuries large portions of the earth have experienced great changes (30) climate.
A、what
B、howC、which D、that