It is d because the law was passed around 1976 I am not sure but this is the best estimate
Answer:
D. El Parque Nacional Yellowstone pronto estará bajo un nuevo liderazgo
Through my research I found matching questions with similar answers:
A) macrophages
B) antigens
C) antibodies
D) lymph
The best answer to fill in the blank would be the third option C) Antibodies which in the name anti means against, so since the word anti is the same as against, its a battle between antibodies and invaders, so that's why its C).