Question

Question was provided via image upload.

Explanation:

Identify the biological barrier breached

The skin acts as the primary physical barrier preventing pathogens from entering the body. This physical barrier is classified as the first line of defense in the immune system.

Determine the correct term

When Steve cut his hand deeply, his skin (the physical barrier) was broken. Therefore, his first line of immune defense was breached.

Answer:

Type the correct answer in the box. Spell all words correctly.

Fill in the box with one of the following words: first, second, third.

Steve cut his hand deeply while working, and the wound became infected. When Steve first cut his hand, his <blank>first</blank> line of immune defense was broken.