Afriend of yours is considering two cell phone service providers. provider a charges $120 per month for the service regardless of the number of phone calls made. provider b does not have a fixed service fee but instead charges $1 per minute for calls. your friend's monthly demand for minutes of calling is given by the equation qd=150−50p, where p is the price of a minute. your friend would obtain in consumer surplus with provider a and in consumer surplus with provider b. given this information, which provider would you recommend that your friend choose?