When people receive organ transplants, they often need to take medications that decrease immune responses because:
(1) transplanted organs contain antigens that can trigger white blood cell activity
(2) hormones present in replacement organs prevent the synthesis of antibiotics
(3) transplanted organs produce their own antibiotics
(4) antigens present in these organs attack antibodies already present in the blood

Option 1

Explanation:

The organ transplanted is a foreign element for the body and the medication prescribed after transplantation surgery prevents this organ from the attack of immune system of the body.

Since the immune system is in habit of attacking all foreign agents, it poses highest risk in transplantation surgery and hence effective medication can prevent the organ form being rejected.  

In general, immuno-suppressant or anti-rejection drugs are given to the patient. Along with anti-rejection drug some additional drugs are given to eradicate the side effects of anti-rejection drugs.

Hence, option 1 is correct

1. dermis

2. chemical

3. urine

4. viruses

5. antibodies

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.