managers of exxon mobil fueling stations keep track of prices at competitor stores such as BP and Shell knowing that a decrease in fuel prices at these other outlets will most likely a. increase the income effect for exxon mobil's fuel products b decrease the income effect for exxon mobil's fuel products c. increase the demand for exxon mobil's fuel products. d. decrease the cross-price elasticity of exxon mobil's fuel products. e. decrease demand for exxon mobil's fuel products if it does not alter its prices