Which is known as Pond Scum/mermaids tresses?

Which is known as Pond Scum/mermaids trees?

Which is pond scum

Mermaid's purse is

Mermaid's purse refers to

Mermaid's purse refers to

Mermaid's purse refers to

Mermaid's purse refers to

A man is sitting in a boat, which is floating on a pond. If the man drinks some water from the pond, the level of water in the pond:

A man is sitting in a boat which is floating in a pond.If the man drinks some water from the pond ,the level of water in the pond

A man is sitting in a boat which is floating in a pond.If the man drinks some water from the pond ,the level of water in the pond