The correct answer is 2 - Closure by secondary intent - allowing wounds to heal independently without surgical closure is called closure by secondary intent.
Wound closure by primary intention refers to the immediate closure of a wound, typically using sutures, staples, or tissue adhesives.
Wound closure by tertiary intention refers to the delayed closure of a wound left open to heal for an extended period. This method of wound closure is typically used for wounds that are contaminated, infected, or have a significant amount of dead tissue (necrosis) present.
There is no such thing as "closure by quaternary intention."