Final answer:
Invest in the healthcare sector, consumer goods sector, and energy sector, while being cautious about investing in the technology sector during a long period of declining GNP.
Step-by-step explanation:
If you expected a long period of declining GNP (Gross National Product), it would be wise to invest in companies in the healthcare sector, consumer goods sector, and energy sector.
Companies in the healthcare sector tend to be less affected by economic downturns because people still require medical services regardless of the state of the economy. Consumer goods companies also tend to be more resilient during an economic decline as people will still need to purchase essential goods. Energy companies, particularly those involved in renewable energy, may also provide investment opportunities as the demand for alternative energy sources continues to grow.
On the other hand, companies in the technology sector may be more susceptible to economic downturns as consumer spending on electronics and high-tech gadgets tend to decrease during these periods.