Solution:Puccinia graminis is a fungus that affects plant stems. It is an obligate parasite of wheat. It causes dark reddish-brown pustules on both sides of stems, leaves, and spikes. Albugo causes white rust.
The stem rust is also known as the lack of rust. The stem rust is caused through the fungus called Puccinia graminis f. sp. tritici. It infects wheat and other cereals across all U.S. growing regions. The black rust can be visually identified as a thin, black film that is due to the oxidation in a low oxygen environment. The black rust has an appearance of almost a black stain. Most likely the areas exhibiting the black rust had something covering them, that prevented the oxygen from reaching the surface.
Hence, option 1 is the correct answer.