The statement A is incorrect. The larger the subcarrier spacing [1], the shorter the symbol duration on each subcarrier, not the larger number of symbols. Statement B is also incorrect. The larger the subcarrier spacing [1], the larger the CP length and the more suitable it becomes for wide coverage. Statement C is correct. The smaller the subcarrier spacing, the lower the power spectral density. Statement D is incorrect. The larger the subcarrier spacing [1], the shorter the slot length.

1. A novel timing and frequency offset estimation algorithm for filtered ...

https://asp-eurasipjournals.springeropen.com/articles/10.1186/s13634-020-00696-1

Extended Cyclic Prefix - an overview | ScienceDirect Topics

https://www.sciencedirect.com/topics/engineering/extended-cyclic-prefix

5G NR Numerology - Subcarrier Spcaing (SCS) - Techplayon

http://www.techplayon.com/5g-nr-numerology-subcarrier-spcaing-scs/