You can use the FOIL method to solve: multiply FIRST, multiply OUTSIDE, multiply INSIDE, multiply LAST to help remember to multiply all terms.
=(4x - 5)(4x + 5)
multiply first term by first term, multiply outside by outside, inside by inside, last by last
=(4x*4x) + (4x*5) + (-5*4x) + (-5*5)
multiply terms
=16x^2 + 20x - 20x - 25
combine like terms
20x cancels itself out
=16x^2 - 25
ANSWER: B) 16x^2 - 25
Hope this helps! :)