Mitochondrial matrix.
In the mitochondrion, the matrix is the space within the inner membrane. ... The enzymes in the matrix facilitate reactions responsible for the production of ATP, such as the citric acid cycle, oxidative phosphorylation, oxidation of pyruvate and the beta oxidation of fatty acids.

Introduction:
The tricarboxylic acid (TCA) cycle, also known as the citric acid cycle or Krebs cycle, is a central metabolic pathway that occurs in the mitochondria of eukaryotic cells. It is an essential part of cellular respiration, which generates energy in the form of ATP. The TCA cycle consists of a series of enzymatic reactions that oxidize acetyl-CoA, producing NADH and FADH2, which are then used in oxidative phosphorylation to generate ATP.

Explanation:
The correct answer is option 'b', which states that most of the enzymes of the TCA cycle are present in the mitochondrial matrix. Let's understand why this is the case:

Mitochondrial Structure:
Mitochondria are double-membrane-bound organelles found in eukaryotic cells. They have an outer membrane and an inner membrane, with an intermembrane space between them. The inner membrane contains numerous folds called cristae, which increase the surface area for various metabolic processes.

The TCA Cycle:
The TCA cycle takes place in the mitochondrial matrix, which is the space enclosed by the inner membrane. The cycle consists of a series of enzymatic reactions that occur in the matrix and are catalyzed by specific enzymes.

Enzymes involved in the TCA cycle:
1. Citrate Synthase: This enzyme catalyzes the formation of citrate from acetyl-CoA and oxaloacetate. It is located in the mitochondrial matrix.
2. Aconitase: This enzyme converts citrate to isocitrate. It is also present in the mitochondrial matrix.
3. Isocitrate Dehydrogenase: This enzyme catalyzes the conversion of isocitrate to alpha-ketoglutarate. It is found in the mitochondrial matrix.
4. Alpha-Ketoglutarate Dehydrogenase: This enzyme converts alpha-ketoglutarate to succinyl-CoA. It is located in the mitochondrial matrix.
5. Succinyl-CoA Synthetase: This enzyme catalyzes the conversion of succinyl-CoA to succinate. It is present in the mitochondrial matrix.
6. Succinate Dehydrogenase: This enzyme converts succinate to fumarate. It is embedded in the inner membrane of the mitochondria.
7. Fumarase: This enzyme converts fumarate to malate. It is also present in the mitochondrial matrix.
8. Malate Dehydrogenase: This enzyme catalyzes the conversion of malate to oxaloacetate. It is located in the mitochondrial matrix.

Conclusion:
In conclusion, most of the enzymes of the TCA cycle are present in the mitochondrial matrix. These enzymes catalyze the various reactions of the cycle, which occur in the matrix and ultimately lead to the generation of ATP through oxidative phosphorylation.

Mitochondria except succinate dehydrogenase.