Final answer:
All the statements about ecological pyramids in the student's question are actually true. Energy pyramids cannot be inverted due to the laws of thermodynamics, while those of standing crop and numbers can be inverted as they do not directly show energy flow in the ecosystem. Saprophytes are not usually included in ecological pyramids although they play an important role in nutrient cycling. Therefore, the correct option isD.
Step-by-step explanation:
The student's question pertains to the characteristics of different ecological pyramids: pyramids of energy, biomass, and numbers. Statement (a) is correct; pyramids of energy and yearly biomass production cannot be inverted, as this would indeed violate the laws of thermodynamics, specifically the first and second laws, which state that energy can neither be created nor destroyed and that in any energy transfer or transformation, some of the energy becomes unusable, respectively.
Statements (b) and (c) are true. The pyramids of standing crop and numbers can be inverted, as these pyramids show the amount of organism at any one moment and do not represent the flow of energy through the system. Examples of this include temperate forests during the summer for numbers and phytoplankton in the English Channel for biomass. Lastly, statement (d) is correct; saprophytes are usually not represented in ecological pyramids despite their critical role in decomposing dead organisms and recycling nutrients within ecosystems.
Therefore, the answer to the question is (d) none of these, as all the statements provided are in fact true.