Macbook and 4K monitor Please, does anyone know whether Macbook (2015) with MacOS Sierra (10.12) is able to drive Dell P2415Q 4K (3840x2160) monitor at 60Hz? What dongles do I need?

I have USB-C Digital AV Multiport Adapter which is said to support "UHD (3840 by 2160) at 30Hz". But Apple's Using 4K displays, 5K displays, and Ultra HD TVs with your Mac states:


  With macOS 10.12 or later, MacBook (2015 and later) and MacBook Pro (2016 and later) support these resolutions and refresh rates over HDMI 1.4b using the USB-C Digital AV Multiport Adapter:
  
  
  4096x2304 at 48Hz refresh rate
  3840x2160 at 60Hz refresh rate (mirroring is not supported at this resolution)
  
  
  MacBook (2016 and later) and MacBook Pro (2016 and later) support 60Hz refresh rates over HDMI when used with a supported HDMI 2.0 display, an HDMI Premium Certified cable, and a supported USB-C to HDMI 2.0 adapter.


So I'm confused now: would it work somehow? Would it work over HDMI? Would it work over DisplayPort? Is the adapter I have suitable?
Answer is yes with the right USB C to DP adapter. I have a 2015 MacBook and I have tried it with two very different 4K displays - one Philips, one LG - and both worked correctly at 4K 60Hz. If fact, they work in Bootcamp, too at 4K 60hz. Impressive. 

FYI, I understand this capability arrived with the Sierra MacOS update. Earlier MacOS versions limit you to 30Hz on this MacBook.

I use a Club3D branded adapter.