Option (c) is the correct answer as it continues the idea of experiences that Second Life offers: ‘these experiences’ refer to ‘types of experiences’ discussed in the last line. Option (a) is incorrect as it breaks the link of the paragraph by discussing business and user groups. Both options (b) and (d) can seem close. However, options (b) and (d) build upon an idea that needs to be expressed first, viz. option (c). First, we need to state that these experiences are created collaboratively by the residents only then can we bring in option (b) or (d). Option (b) is a conclusion about Second Life being an experiment in collaborative experience innovation. Option (d) mentions how Linden Labs provides tools to the residents to create these experiences.