Explanation:
The pyramid of biomass represents the relationship between the biomass and trophic levels in an ecosystem. It can either be upright or inverted depending on the type of ecosystem.

- Pyramid of Biomass for Aquatic Ecosystem: The pyramid of biomass for an aquatic ecosystem is usually inverted. This is because in the aquatic ecosystem, the producers (phytoplankton) have a rapid turnover rate and are consumed quickly by herbivores. The herbivores are then consumed by carnivores, but the biomass decreases at each trophic level due to energy loss. Therefore, the biomass of the producers is less than that of the herbivores and so on, resulting in an inverted pyramid of biomass.

- Pyramid of Biomass for Forest: The pyramid of biomass for a forest ecosystem is upright. This is because the biomass of producers (trees) is much higher than that of their consumers (herbivores). As we move up the trophic levels, the biomass decreases due to energy loss. Therefore, the biomass of the producers is much greater than that of the herbivores and so on, resulting in an upright pyramid of biomass.

- Pyramid of Number for Aquatic Ecosystem: The pyramid of number for an aquatic ecosystem can be either upright or inverted depending on the type of ecosystem. In a pond ecosystem, the pyramid of number is usually upright since the producers (phytoplankton) are present in large numbers and are consumed by a smaller number of herbivores. As we move up the trophic levels, the number of individuals decreases due to energy loss. Therefore, the number of producers is much greater than that of the herbivores and so on, resulting in an upright pyramid of number.

- Standing Crop: The standing crop is the amount of living organisms present in a particular area at a particular time. It is measured in terms of biomass or sometimes in terms of number. It represents the amount of energy available to the next trophic level.

Therefore, option 'A' is incorrect as the pyramid of biomass for an aquatic ecosystem is usually inverted.

Pyramid of biomass for aquatic ecosystem is upside down so the statement A is incorrect