Answer:a leech
Explanation: a parasitic relationship is one organism benefit on the other while the other is harmed
It creates oxygen which every living thing needs to live. i hope this helps! :)
To calculate an electron configuration, divide the periodic table into sections to represent the atomic orbitals, the regions where electrons are contained. Groups one and two are the s-block, three through 12 represent the d-block, 13 to 18 are the p-block and the two rows at the bottom are the f-block.
