What is the main difference between the Brand Awareness and Engagement objectives?

What is the main difference between the Brand Awareness and Engagement objectives?
A . Brand Awareness optimizes for ad recall white Engagement optimizes for likes/shares/comments
B. Brand Awareness optimizes for likes/shares/comments,while Engagement optimizes for ad recall
C. Brand Awareness optimizes for conversions, white Engagement optimizes for views
D. Brand Awareness optimizes for views, while Engagement optimizes for conversions

Answer: A