The flow of energy in a pyramid of food is represented by the figure given. In this ecosystem, the energy starts from the primary producers, which are usually plants, and flows through various trophic levels until it reaches the tertiary consumer. Let's analyze each level and calculate the amount of energy available to the tertiary consumer.

1. Primary Producers:
The primary producers, represented by the green plants in the figure, receive 100,000 kcal of sunlight energy. They use this energy through the process of photosynthesis to produce organic compounds. However, not all of this energy is transferred to the next level. A significant portion is used by the plants for their own metabolic processes, such as respiration. Let's assume that 10% of the energy is transferred to the next level.

2. Primary Consumers:
The primary consumers, represented by the herbivores in the figure, consume the primary producers. They obtain energy by digesting the plant material. Again, not all of the energy is transferred to the next level. Let's assume that 10% of the energy is transferred.

3. Secondary Consumers:
The secondary consumers, represented by the carnivores in the figure, feed on the primary consumers. They obtain energy from the prey they consume. Once again, not all of the energy is transferred to the next level. Let's assume that 10% of the energy is transferred.

4. Tertiary Consumers:
Finally, we reach the tertiary consumer, represented by the apex predator in the figure. They are at the top of the food chain and feed on the secondary consumers. The energy available to them is further reduced due to energy losses at each trophic level. Assuming a 10% transfer of energy, the amount of energy available to the tertiary consumer is 1% (10% of 10%) of the initial sunlight energy received by the primary producers.

Therefore, the energy finally available to the tertiary consumer is 1,000 kcal (1% of 100,000 kcal).

In conclusion, the correct answer is option D) 1 kcal.