question: What is the main objective of the 3GPP study item titled 'Study on new radio network energy saving enhancements'? option 1: Investigate the benefits of machine learning in energy saving option 2: Develop a power consumption model for 5G user equipments option 3: Increase the energy efficiency of data centres option 4: Improve the energy consumption of fiber transport option 5: Identify new energy saving scenarios beyond capacity booster cells 