Compensation point is

The figure shows the effect of light on the rate of photosynthesis. Based on the graph,answer the following questions:
$(a)$ In which region/s (indicated by arrows) is light a limiting factor?
$(b)$ What could be the limiting factor/s in the region where the rate of photosynthesis becomes constant?
$(c)$ What does the point where the curve flattens represent?

The Law of Limiting Factors was proposed in which year?

Generally,atmospheric $CO_2$ is not a limiting factor for hydrophytes because...

$A$ plant is kept in $300 \, ppm$ $CO_2$ concentration. What will happen to it?

Photosynthetic organisms occur at different depths in the ocean. Do they receive qualitatively and quantitatively the same light? How do they adapt to carry out photosynthesis under these conditions?