Above is an example of a food chain or pyramid. Ultimately, either directly or indirectly all organisms on this food chain get their energy from what single source?

The ultimate energy of a food chain/pyramid comes from the sun.

The sun provides energy for plants, the primary producers, which are consumed by, and thus transfer energy, to the secondary consumers, which transfer energy to the tertiary consumers, and so on. When these organisms die, detritivores and decomposers break down the remains.