The base piece of F${}_1$ particle are embedded in the inner mitochondrial membrane, while the headpiece containing the enzymes of ATPase is facing

The correct option is D The mitochondrial matrix
The elementary particles or F${}_1$ particles or oxysomes were first isolated by E Racker in 1961. The structures are present on the inner mitochondrial membrane. It consists of a spherical head and a base piece. It is useful in several processes of cellular respiration and used for the regeneration of ATP from ADP and phosphate. The spherical headpiece faces the mitochondrial matrix where it synthesizes the ATP and releases into the mitochondrial matrix.