In 1992, the bilateral agreement of the U.S. with the European Union regarding the subsidies for production of civil aircraft included that : a. direct government support for new airplane development are limited to one- tenth of the total development costs. b. indirect government support is limited to four percent of a firm’s civil aircraft sales. c. only production but no marketing subsidies could be provided to the firm. d. subsidies could only be in the form of loans at a market rate of interest with a short repayment period.