The word in bold “easy” in line 16 is a/an:
Probiotics and Prebiotics: What’s Really Important

(Available at: https://www.health.harvard.edu/nutrition/are-you-getting-essential-nutrients-from-your-diet/ - text especially adapted for this test).
Probiotics and Prebiotics: What’s Really Important

(Available at: https://www.health.harvard.edu/nutrition/are-you-getting-essential-nutrients-from-your-diet/ - text especially adapted for this test).