Suppose you have the job of assigning the proper number of house of representatives seats for various states. to do that, you must know the in that state.
a. number of counties
b. population
c. apportionment
d. number of districts

The number of seats in the House of Representatives depends on the population, but not directly: it depends on the population as compared to the other states. Based on the population, the number is being apportioned (aloted), roughly proportionally to the population.

So b.population would be good for a rough estimate, but the actual answer is c.

River arrow on this map is pointing

Ghana, first of the great medieval trading empires of western africa (fl. 7th–13th century). it was situated between the sahara and the headwaters of the sénégal and niger rivers, in an area that now comprises southeastern mauritania and part of mali.