An American worker is hired by a German consulting firm operating in New York. They pay him $50,000 in wages. The new worker's contribution is to bring a new client to the firm that buys consulting services for $70,000 . Assume no other new cost was involved in this other than the wage. The client is a Mexican firm located in Mexico City. Which of the following is correct

a. National income increases by $50,000 and factor payments to abroad increase by $20,000, so US GDP increases by $70,000
b. Consumption increases by $70,000 and imports increase by $70,000,50 US GDP remains unchanged
c. Consumption increases by $50,000 and exports increase by $20,000, so US GDP increases by $70,000
d. National income increases by $50,000 and factor payments from abroad increase by $50,000, so US GDP remains unchanged