This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
A patient with grossly contaminated wound presents 12 hours after an accident. His wound should be managed by - 
Select and explain. 
A. Thorough cleaning and primary repair, B. Thorough cleaning with debridement of all dead and devitalised tissue without primary closure, C. Primary closure over a drain, D. Covering the defect with split skin graft after cleaning
B: Thorough cleaning with debridement of all dead and devitalised tissue without primary closure
Answer: B: Thorough cleaning with debridement of all dead and devitalised tissue without primary closure 
Explanation: Any wound can be closed by
primary suture or
delayed primary suture or
left open to heal by secondary closure

Primary suture is suitable for

clean wounds &
selected contaminated wounds after thorough wound toileting & debridement

Delayed primary closure is done for

heavily contaminated wounds
wounds in which wound toileting has been delayed for 6-8 hrs.
But these were the indications earlier. Now the recent approach is:
if the blood supply to the wound is adequate and bacterial invasion is absent, wounds can be safely closed anytime following proper debridement & irrigation. 
if there is established infection and tissue of doubtful viability has been left in situ, then the wound is left open and re-explored after 48 hrs. If there is no infection, and the doubtful viable tissue is now healthy, the deep tissues can be repaired & the wound closed. If however there is further necrosis & infection the wound is again debrided & left open.