You are evaluating different data sources for an upcoming campaign. Match the campaign objectives and funnel stages with the most appropriate data sources:
- Objective/Stage I: Increasing brand awareness on social media.
- Objective/Stage II: Measuring the effectiveness of an email marketing campaign for lead nurturing.
- Objective/Stage III: Assessing the reach and initial interest of a new product launch campaign.
- Objective/Stage IV: Evaluating the conversion rate from a recent PPC advertising campaign.
Identify the most suitable data sources for each campaign objective or funnel stage.