Photosynthetic cyanobacteria caused an increase in atmospheric levels of a) ozone b) water c) oxygen d) carbon dioxide.

C...the key is that they are photosynthetic...so they produce oxygen (like plants)!

characterization of nanoparticles is a critical step in nanomaterial production as it provides information of dimension, morphology, surface charge, distribution and degree of surface functionalization.

kelp are large brown algae that live in cool, relatively shallow waters close to the shore. they grow in dense groupings much like a forest on land. these underwater towers of kelp provide food and shelter for thousands of fish, invertebrates, and marine mammal species.

e) all of the above