Question

all of the organs of the respiratory system are built of... cells, which are made of tissues. tissues, which are made of cells. blood and skin tissues. blood and skin cells.

Explanation:

To solve this, we recall the biological organization: cells form tissues, tissues form organs. So organs (like respiratory organs) are made of tissues, and tissues are made of cells. Let's analyze each option:

• First option: Cells are made of molecules, not tissues (tissues are made of cells), so wrong.
• Second option: Tissues (made of cells) make up organs, which matches the biological hierarchy.
• Third option: Respiratory organs aren't made of blood and skin tissues (skin is part of integumentary system, blood is connective tissue but not main for respiratory organs' structure), wrong.
• Fourth option: Respiratory organs aren't made of blood and skin cells, wrong.

Answer:

B. tissues, which are made of cells. (Here we assume the second option is labeled as B; if the original options had different labels, adjust accordingly. Since the options are presented as radio buttons, the correct one is "tissues, which are made of cells".)