The correct option is A Claviceps
Fungal disease of cereal grasses like rye is caused by the ascomycete fungus Claviceps. It contaminates the harvest and decreases the production of viable grains.
Phytophthora causes potato blight.
Uncinula is a fungus that causes powdery mildew of grapes.
Loose smut of barley is caused by Ustilago.