A Human Resources (HR) firm finds that a new service has entered the market which helps employees in the workplace find quick automated answers to most of their questions. The claim of the producers of this new service is that it will complement Human Resource functions rather than substitute them. Which of the following will indicate that the new service is a close substitute of the HR firm? a) The cross-price elasticity is negative b) The income elasticity is negative c) The income elasticity is positive d) The cross-price elasticity is positive and greater than one