Here's why:

* Mitochondria: The powerhouse of the cell, where cellular respiration takes place.

* Inner mitochondrial membrane: The inner membrane of the mitochondria is the site of the electron transport chain, a key process in cellular respiration.

* SDH's role: SDH is a crucial enzyme in the citric acid cycle (also known as the Krebs cycle), a stage in cellular respiration that occurs in the mitochondrial matrix. However, SDH is actually embedded in the inner mitochondrial membrane, acting as a bridge between the matrix and the electron transport chain.

Let me know if you have any other questions!