Final answer:
Emma is required to manually add text assets when creating a new app campaign. Text is essential for providing engaging details about the app and is a fundamental element to any ad campaign that she must create.
Step-by-step explanation:
When Emma is creating a new app campaign, she is required to manually add certain types of ad assets. Among the options provided, the asset type that she would need to manually add is text.
While images and videos may also be added, platforms often provide the option for dynamic ad generation based on existing assets and ad performance data. It is important for Emma to include engaging and informative text that aligns with her app's branding and call to action to attract potential users.