Lissom means (of a person or their body) thin, supple, and graceful.
Ex: the kind of outfit that should be left to lissom teenagers
Slow means moving or operating, or designed to do so, only at a low speed; not quick or fast.
Ex: until recently diesel cars were slow and noisy
Honest means free of deceit; truthful and sincere.
Ex: I haven't been totally honest with you
Supple means bending and moving easily and gracefully; flexible.
Ex: her supple fingers
Dull means lacking interest or excitement.
Ex: your diet doesn't have to be dull and boring
Thus option (C) is the correct choice.