The idea of the productivity of an ecosystem can be obtained from:

Which of the following ecosystem types has the highest annual net primary productivity?

Given below are two statements:
Statement $I$: The primary source of energy in an ecosystem is solar energy.
Statement $II$: The rate of production of organic matter during photosynthesis in an ecosystem is called net primary productivity $\text{(NPP)}$.
In the light of the above statements,choose the most appropriate answer from the options given below:

Total amount of the dry weight of photosynthate produced by all types of plants per annum is:

Primary productivity is defined as:

Primary productivity varies from ecosystem to ecosystem. Explain.