Answer:
A) The presence of iron oxides (rust) in sedimentary rock layers that are 2 billion years old.
Explanation:
- Cyanobacteria are aquatic and photosynthetic ,they live in water and manufacture own food releasing oxygen as a by product and in which most living organisms depend on.
- Cyanobacteria are found in the ocean and are believed to be responsible for the formation of the iron oxide found on the sedimentary rocks since they release oxygen as a by product and it is used in the iron oxide formation process below the level of wave disturbance.
B horizon lies below A horizon in mature soils so this layer is characterized by an accumulation of clay.
<u>Explanation:</u>
B horizon: are usually alluded to as the subsoil. It has the most parts made of clay, iron minerals as well as organic matter, which have been washed down to this horizon by rainwater. It is slim in certain specks of dirt, thick in others, and not present at all in others.
The clay comprises of little particles under 0.002 mm and 0.00008 inches in diameter. It additionally collects a lot of natural issues this results the way that it gathers the mass of dead and rotting matter of plants and creatures.