Pond silk or water silk is the common name of a. Nostac b. spirogyra
c. chalamydomonas d. peziza

B

Explanation:

Spirogyra is free-floating green algae present in freshwater habitats such as ponds, lakes, etc. Spirogyra is commonly known as water silk or pond silk. They have a filamentous and unbranched vegetative structure.

or

Spirogyra forms a silk like layer on the water. It is present in abundant amount on the fresh water bodies or slow running water. They are slippery in nature, so are commonly known as pond silk or water silk.

weathering - colorado river carves land in arizona to form the grand canyon. cracks form in a sandstone wall surrounding a house. a marble statue near the science museum is changing color due to rainfall

erosion - after a rainstorm, soil and rock piees litter the roadways. the sand dunes in the sahara desert are changing shape.

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