Which cable type must be used to interconnect one switch using 1000 BASE-SX GBIC modules...

LC to SC. 1000BASE-SX GBIC modules commonly use SC connectors, while 1000BASE-SX SFP modules commonly use LC connectors. When interconnecting a GBIC-based switch to an SFP-based switch, the fiber patch cable must therefore have LC on one end and SC on the other. LC-to-LC would fit two SFP-style interfaces, and SC-to-SC would fit two GBIC-style interfaces. Cisco CCNA 200-301 v1.1 Network Fundamentals expects engineers to recognize not only fiber standards but also connector differences across transceiver types. The corrected answer is LC to SC. Both ends still use the same optical Ethernet standard, but the physical connector form factor differs between the GBIC and SFP modules.