Which of the following statements is incorrect?

• A
  Plants capture $2-10 \%$ of the photosynthetically active radiation $(PAR)$.
• B
  The first law of thermodynamics is not applicable to ecosystems.
• C
  The second law of thermodynamics explains why energy must be constantly supplied to ecosystems.
• D
  The standing crop is measured in terms of biomass or number per unit area.