As we age, losses occur in some domains, while gains are made in others. this is consistent with the nature of development.

Answer;
As we age, losses occur in some domains, while gains made in others. This is consistent with the multidirectional nature of development.

Explanation; 
Human development is multidirectional which means it occurs in many different dimensions, including biological, cognitive and socio-emotional aspects. Development is embraced as a continuity of change that produces  both gains and losses which proves to enhance future changes. 

The answer is c) tons