The process that occurs in the structures marked with X is the Krebs cycle (last option).
Explanation:
The Krebs cycle is a process by which energy in the form of ATP is produced from pyruvate molecules obtained by transformation of glucose, which occurs in the mitochondria, marked with X in the diagram (see image).
The mitochondria is a specialized organelle, whose function is the production of energy within the cell. It has a membrane on the outside that allows the passage of proteins, energetic substrate and ions, and inside it crests are formed where the energetic synthesis takes place.
The answer is letter C. The distribution of oak trees in an
area.
Population Ecologist would often measure the number
distribution and density of the area. Trees are often measured by plots or by
hectares. This is to know how many trees are situated in that
area.