• HAT Medium Selection Mechanism:
• HAT medium contains Hypoxanthine, Aminopterin, and Thymidine:
• Aminopterin: A potent folate analog that blocks dihydrofolate reductase (DHFR), shutting down de novo synthesis of purines and thymidylate.
• Hypoxanthine & Thymidine: Allow cells to survive via salvage pathways if they possess functional salvage enzymes:
• HGPRT (Hypoxanthine-guanine phosphoribosyltransferase) for purine salvage.
• TK (Thymidine kinase) for pyrimidine salvage.
• In hybridoma generation, parent myeloma cells deficient in HGPRT (or TK) die in HAT medium. Primary spleen cells cannot divide indefinitely in culture. Only hybrid cells, which inherit functional HGPRT/TK from B cells and immortality from myelomas, survive.

Correct option: (1) Thymidine kinase and Hypoxanthine guanosine phosphoribosyl transferase