Identify whether the following scenarios represent Pull or Push growth channels, and then further categorize them as Direct, Indirect, Discovery-Driven, or Virality-Driven:
- Scenario I: A business sponsors a popular podcast to mention their product.
- Scenario II: An online store uses SEO tactics to rank higher in search engine results.
- Scenario III: A brand creates a hashtag challenge on social media to engage users.
- Scenario IV: A company sends out a promotional email to its subscriber list.
Match each scenario with the correct category of growth channel.