Airlines are already increasing their price on the （ ） that fuel prices are going to rise.
航空公司正在提升他们的价格，假设油价正在上涨。On the assumption that 假设，固定搭配。A 选项，消费；B 选项，破坏；D 选项，放肆，傲慢，推测。选择 C 项。