The answer is d. the ability to transmit light; for example, air
Transparency means allowing light to pass through the material. Thus, the transparent material must be able to transmit light. Air is transparent. It is a gas containing very few atoms, so light run into few of them and thereby air looks transparent.
<u>A</u>. Lymph nodes produce antibodies and aid the the removal of pathogens. Without functional lymph nodes, the individual would be significantly more vulnerable to being harmed by common viruses.