Which Windows version was the last to have a 16-bit kernel?

Which Windows version was the last to have a 16-bit kernel? Windows 95 is the best canonical answer. Its kernel was fundamentally 32-bit, but substantial 16-bit system code remained for compatibility and development reasons.

Windows 95 marked Microsoft's transition from the 16-bit Windows architecture of Windows 3.x to a hybrid 16/32-bit design. Its Win32 environment and preemptive multitasking were major changes, while Win16 support and legacy system components remained.

Windows 98 and Windows Me continued the Windows 9x architecture and also retained compatibility-oriented 16-bit components. Therefore, the wording is technically imprecise if “16-bit kernel” means an entirely 16-bit kernel. Among the listed options, however, Windows 95 is the standard historical answer associated with the last major transition from the 16-bit kernel era.