Coral reefs have the highest productivity among the given options.

Explanation:

Productivity of an ecosystem is defined as the rate of biomass production or the amount of organic matter produced per unit area per unit time. It is influenced by various biotic and abiotic factors such as temperature, light, water availability, nutrient availability, etc.

Coral reefs are highly productive ecosystems due to the following reasons:

1. High Solar Radiation: Coral reefs are found in shallow waters where they receive high solar radiation, which is essential for photosynthesis and hence, primary productivity.

2. Nutrient Availability: Coral reefs are located in nutrient-poor waters, but they have a unique nutrient recycling system that helps to retain and recycle nutrients efficiently. The coral animals and algae living on the reefs recycle nutrients, and the coral reef ecosystem acts as a nutrient bank, providing nutrients to support the growth of other organisms.

3. Biodiversity: Coral reefs support a high diversity of species, including fishes, invertebrates, and algae. This high diversity contributes to the productivity of the ecosystem as each species has a unique role in the ecosystem, and the interactions between them result in efficient nutrient cycling and energy flow.

4. Efficient Energy Transfer: Coral reefs have a high transfer efficiency of energy from primary producers to consumers due to the presence of many small-sized organisms that are easily consumed by larger organisms. This efficient energy transfer results in high productivity of the ecosystem.

Hence, due to the above reasons, coral reefs have the highest productivity among the given options.

After tropical rain forest,Coral reefs has 2nd lagest diversity on Earth..!!