Question: What is the maximum number of SC-FDMA symbols that can be used for guard period creation for Tx-to-Tx frequency retuning between two consecutive subframes for BL/CE UEs?
Option 1: 2
Option 2: 4
Option 3: The value of higher layer parameter ce-RetuningSymbols, if set; otherwise, 
Option 4: 8
Explanation: According to the text, for BL/CE UEs, a guard period of at most SC-FDMA symbols is created for Tx-to-Tx frequency retuning between two consecutive subframes. The number of SC-FDMA symbols used for guard period creation depends on the value of higher layer parameter ce-RetuningSymbols, if set; otherwise, .