Given Statement:    A = B = C ≥ D ≥ E ≥ F = G = H

For C1, we can see that between C and F the common sign is of '≥' which means C1 individually doesn't follow.
But if we look at C2 which is B = G (or C = F because we have B = C and G = F), we can say that either C1 or C2 follows.

Now, between H and D the common sign is of '≤' (while moving from H to D), which is given as C3.

Hence C3 completely follows.