Review the following scenarios involving the testing of Pull Channels for user growth and identify which scenario(s) demonstrate an effective testing approach:
- Scenario I: A company measures the success of its blog content by the number of articles published each month.
- Scenario II: A brand tracks the increase in organic search traffic and user engagement as a result of its new SEO strategy.
- Scenario III: A business evaluates the effectiveness of its social media campaigns based on the growth in followers and the level of user interaction.
- Scenario IV: An online community's success is gauged by the number of new threads created.
Select the scenario(s) that correctly apply effective testing methods for Pull Channels.