( A ) $Pistia \to Volvox \to Scirpus \to Hydrilla \to Oak \to Lantana$
( B ) $Oak\to Lantana \to Scirpus \to Pistia \to Hydrilla \to Volvox$
( C ) $Oak\to Lantana \to Volvox \to Hydrilla \to Pistia \to Scirpus$
( D ) "$Volvox\to Hydrilla\to Pistia\to Scirpus\to Lantana\to Oak$"