Question

which challenges do countries face in limiting the spread of communicable diseases?
lack of available healthy food
increase of worldwide travel
decrease of available clean water
increase in migration of infected animals

Explanation:

An increase in worldwide travel allows infectious agents to be easily transported across regions and borders, facilitating the spread of communicable diseases. Lack of healthy food and decrease in clean - water are more related to general health issues and disease susceptibility rather than directly to disease spread. While animal migration can play a role, the global scale and frequency of human travel make it a more significant challenge in limiting communicable disease spread.

Answer:

increase of worldwide travel