Toadstool (poisonous mushroom) is
A. Ganoderma
B. Phallus
C. Amanita
D. Morchella

Hint: The mushrooms(Agaricus) belong to Kingdom Fungi of class Agaricomycetes. Mushrooms can be either edible or inedible based on whether they are poisonous or not. They are also known as toadstools.

Step by step answer:Mushrooms are spore-bearing fruiting bodies fungus which has a rounded cap on the top of the stalk. Toadstools are called so because of the shape they have looked like a perfect place for toads to sit on. Toadstools refer to those mushrooms which are toxic, poisonous, and are inedible.
-Ganoderma lucidum also called reishi mushroom is generally consumed by healthy people to boost the immune system and by cancer patients during their therapies because of its anti-cancer properties. This shows that it's edible and hence cannot be the answer.
-Phallus impudicus also is known as stinkhorn because their odor is such that it can knock you down however these are not at all poisonous or harmful to animals or plants. It is edible and is used highly in Chinese cuisine.
-Amanita is known as Toadstool as consuming this mushroom is harmful. It takes about 5-24 hours for the symptoms to appear which include diarrhoea, liver, kidney failure, convulsions, and can often lead to death.
-Morchella esculenta is a genus that includes edible mushrooms which are also known as, true morel, yellow morel, Guchi, sponge morel, common morel, it is one of the most important(economically) species of wild mushrooms.
So option C is the correct answer.

Note: A mushroom or agaric is that the fleshy, spore-bearing plant organ of plant life, usually seen on top of the ground, on soil, or its food supply. Toadstool is an associate pseudoscientific label that's typically applied to forms of mushrooms. It always refers to colorful and toxic or unpalatable mushrooms.