A ________ Can Be a Very Challenging Injury for the Immune

A ________ can be a very challenging injury for the immune system to respond to because ________.

A) bruise;blood vessels lose so much blood into the surrounding tissues
B) puncture;the first line of defense is immediately bypassed and depending on the depth of the puncture much of the second line may also be ineffective
C) blistering sunburn;the acidity of skin is compromised
D) laceration;the salt and acid on the skin's surface can enter through the wound