Hello there, and thank you for posting your question here on brainly.
Short answer: A. 4 x 28 = n
Why?
You can use context clues. So, Gigi saw n birds, Mike saw 4 times as many birds as Gigi. Times is often referred to as multiplication. What is the only equation that shows times, or multiplication? That'd be A. 4 x 28 = n
Hope this helped you! ♥