Final answer:
Fungi are the type of pathogens that secrete cell wall-degrading enzymes to kill cells and consume their nutrients. The correct option is A.
Step-by-step explanation:
The type of pathogen that kills cells and consumes its nutrients by secreting cell wall-degrading enzymes is Fungi. Fungal pathogens, such as those causing wilt diseases in tomatoes or Dutch elm disease, employ this strategy.
They release hydrolytic enzymes, which break down the structural components of cells, such as the cellulose in plant cell walls, allowing the fungi to absorb the resulting nutrients. This mode of nutrition is typical of fungi, which are often saprotrophic organisms, decomposing and deriving nutrients from dead or decaying organic matter.
However, when they attack live hosts, they can act as necrotrophic pathogens, killing the host cells and feeding on the dead tissue.