Final answer:
A star requires extremely high temperatures and significant mass to fuse heavier elements during supernova nucleosynthesis.
Step-by-step explanation:
The two things a star must have to fuse heavier elements in supernova nucleosynthesis are extremely high temperatures and mass. The immense heat, often several billion degrees, provides the energy necessary to overcome the electromagnetic repulsion between atomic nuclei, enabling them to get close enough for the strong nuclear force to facilitate their fusion. The star's mass must also be sufficiently high, usually more than about 8 solar masses, to create the pressure needed to ignite these fusion reactions.