Plugging in 0 doesn't work so you can automatically rule out option D.
Plugging in 1 is an easy one. 5.6 + 0.4(1) is 5.6 + 0.4 = 6. 6(1) is also 6. This rules out option A.
Now all we have to do is plug in 0.875 to see if it works. If it does, option C is the answer. If not, well... only leaves option B.
5.6 + 0.4(0.875) = 5.6 + 0.35 = 5.95
6(0.875) = 5.25
So 0.875 does not make the statement true.
Your answer is Option B.
