ANS:C - increased reflux ratio

When the feed line (q-line) is moved from the vertical position (saturated liquid feed) to the horizontal position (saturated vapor feed), and the slope of both the operating lines (stripping and rectifying lines) are increased, it will result in increased reflux ratio. Increasing the slope of both the operating lines corresponds to increasing the efficiency of the distillation process. This can be achieved by increasing the reflux ratio, which is the ratio of the reflux (liquid returning from the condenser) to the distillate (product) flow rates. A higher reflux ratio leads to more liquid being returned to the column, which increases the liquid holdup in the column and enhances the mass transfer between the vapor and liquid phases. This increased mass transfer allows for a greater degree of separation to be achieved with a fixed number of trays. So, the correct answer is increased reflux ratio.