Voted for E medium feasibility / medium impact.
I find it very important to visit and talk to merchants personally. This will increase the impact, however, without a strong incentive, it is hard to change people's habits. Identify key people in a community. Convincing them to accept Steem will make it more likely for others to follow. Feasibility depends on the available resources.
On the topic of changing people's habits, I can recommend Charles Duhigg's book "The Power of Habit - Why we do what we do in life and business"