What does the circled node represent?

answer; the correct answer is desert plants;

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.

energy and particles

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.