quizzes: expand all 35 quizzes to 15 questions each

OPS-1 through OPS-10, OS-2, OS-3 went from 5 → 15.
OS-1, OS-4 through OS-11, SEC-1 through SEC-11, TRB-1 through TRB-4 went from 7 → 15.
Questions cover exam-weight scenarios not duplicated from original content.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

quizzes/OS-4-quiz.md

@@ -56,6 +56,62 @@ B. `/?`
 C. `127.0.0.1`  
 D. `C:`  
 
+8. Which command checks and repairs disk errors on a drive?
+
+A. `sfc /scannow`  
+B. `netstat -ano`  
+C. `chkdsk /f`  
+D. `gpresult /r`  
+
+9. A technician wants to see the path network packets take to a remote host. Which command is best?
+
+A. `hostname`  
+B. `whoami`  
+C. `tracert`  
+D. `net use`  
+
+10. Which command maps a network drive to a drive letter?
+
+A. `diskpart`  
+B. `net use Z: \\server\share`  
+C. `gpupdate`  
+D. `sfc`  
+
+11. A PC needs an immediate shutdown. Which command achieves this?
+
+A. `shutdown /r /t 0`  
+B. `shutdown /s /t 0`  
+C. `gpupdate /force`  
+D. `sfc /scannow`  
+
+12. Which command repairs the Windows boot record when a system cannot start?
+
+A. `chkdsk /r`  
+B. `diskpart`  
+C. `bootrec /fixmbr`  
+D. `netstat -ano`  
+
+13. What does `DISM /Online /Cleanup-Image /RestoreHealth` do?
+
+A. Formats the system drive  
+B. Repairs the Windows component store using Windows Update  
+C. Forces a Group Policy refresh  
+D. Stops all running services  
+
+14. Which command terminates a running process by its process ID?
+
+A. `net stop`  
+B. `gpresult /r`  
+C. `taskkill /PID <id> /F`  
+D. `sfc /scannow`  
+
+15. Which command releases the current DHCP lease on a Windows machine?
+
+A. `ipconfig /renew`  
+B. `ipconfig /flushdns`  
+C. `ipconfig /release`  
+D. `ipconfig /all`  
+
 ## Answer Key For Instructor
 
 1. D
@@ -65,4 +121,12 @@ D. `C:`
 5. A
 6. C
 7. B
+8. C
+9. C
+10. B
+11. B
+12. C
+13. B
+14. C
+15. C