Final answer:
Gas gangrene is caused by Clostridium perfringens, while cellulitis is often caused by Streptococcus pyogenes (GAS). Hence, option (3) is correct.
Step-by-step explanation:
Gas gangrene is caused by Clostridium perfringens, an endospore-forming, gram-positive bacterium. It is an obligate anaerobe that grows in tissue devoid of oxygen. Gas gangrene is characterized by rapidly spreading myonecrosis, excruciating pain, foul-smelling wound, and tissue necrosis. It produces toxins that can lead to tissue destruction, gas production, and other severe complications.
On the other hand, cellulitis is often caused by Streptococcus pyogenes, commonly known as Group A streptococci (GAS). It is responsible for cases of cellulitis, erysipelas, and erythema nosodum. Cellulitis is an infection of the deeper layers of the skin, and it often occurs when bacteria enter the skin through a break or crack.