According to developmental psychologist k. warner schaie, verbal ability rises until about the start of the and then stays fairly steady.

40s

Explanation:

According to Schaie's stages of cognitive development,  verbal ability will rise until around the age of 40, which is the stage he refers to as the achieving stage.

In the achiveving stage, the person primary concerns are to fulfill personal goals such as to have a family, establish the career. It does so by using the intellectual skills learned in the former acquisitive stage.

The acquisitive stage lasts from adolescence, includes childhood and keeps developing as a person gathers knowledge and abilities to attain career, personal and social goals.

The fulfillment of this long term objectives includes social skills.

i'll just take the points xd