Equivalent means equal.
So, we need to find expressions that are equal to 8(1+6x)
As we can see, we should use the Distributive Property and distribute 8:
8*1+6x*8 (Option D is the correct option)
8+48x (Option A is also correct)
Hence, Options A and D are correct.
Hope you find it helpful.
Feel free to ask if you have any doubts.