This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to market your social networking site and earn money from it
Choose a specific category or market.
Decide which niche you can cater to. It can be focused on particular group or category like college students of a community, single parents, baby boomers, and the like.

Select from: [I] You can save money by focusing on a single niche instead of wanting to get everyone to join. Potential subscribers will always have the inclination to join in networks of people with like interests and background. [II] Then narrow down the list to compile a solid demographic based on the following : Depth of use of a particular category. Mental stimulation-marketing can reach many different places, so choose wisely. [III] Decide on the niche for your site and set the style that appeals most to you. Your site will need to provide a lot of detailed information to get a sufficient number of people involved and it must have enough content. [IV] The overlapping niche also enables you to get some niche availability in which you're more personally aware of your group's culture and customer base. Look into colleges, universities, community centers, and other places of interest for your group.
The answer is:
[I]