Final answer:
The sequence of crystallization along the discontinuous branch of Bowen's reaction series is a) Olivine → Pyroxene → Amphibole → Biotite.
Step-by-step explanation:
The sequence of crystallization along the discontinuous branch of Bowen's reaction series is a) Olivine → Pyroxene → Amphibole → Biotite. This sequence illustrates the order in which minerals crystallize from a cooling magma. The discontinuous branch reflects the changing mineral composition resulting from the magma's cooling and different minerals becoming stable at different temperatures. As the temperature continues to drop, the crystallization process moves through this specific sequential order starting with the formation of olivine, then evolving to pyroxene, followed by amphibole, and eventually to biotite, each phase reflecting a change in the magmatic composition and temperature.