Concept:Seed germination in a laboratory requires moisture and a suitable temperature.
Explanation:Seeds absorb water to activate enzymes and begin metabolic processes.
Enzymes work best within a certain temperature range, so gentle heat is needed.
Oxygen is also required, but it is already present in the laboratory air.
Microbes are not necessary and may even cause decay.
Soil and manure are not needed because germination does not depend on soil nutrients.
Therefore, the essential pair from the options is heat and water.
Answer:B. heat and water