Final answer:
Saudi Arabia has not been building and improving their nuclear weapons program as a result of selling oil; instead, they have invested in infrastructure, agriculture, and urban development.
Step-by-step explanation:
Among the listed improvements Saudi Arabia has made as a result of selling oil on the world market, building and improving their nuclear weapons program is the action that has not been pursued. Saudi Arabia has indeed invested in modernizing roads, schools, airports, and communication systems (a), implemented strategies to improve the agricultural industry such as billions spent on irrigation and desalinization technology (b), and built cities in previously remote desert areas (c). However, there are no official reports or evidence suggesting that Saudi Arabia has been developing or improving a nuclear weapons program as a result of its oil sales.
Additionally, they have built cities in once remote deserts. However, one improvement that Saudi Arabia has not made as a result of selling oil is building and improving their nuclear weapons program.