Go!

From Twitter:

Without a subject, what is the implied subject in a sentence?
What is the subject in this sentence?

“Go!”

a. I
b. you
c. we
d. no subject is implied


Photo: Nicolas Hoizey

Answer And Explanation:
The answer is b., you, because in an imperative (like a command), the implied subject is always the second person pronoun or proper noun; it is ‘you.’.