What defines whether or not organisms belong to the same species?

During an investigation of an xss attack, the investigator comes across the term "[a-za-z0-9\%]+" in analyzed evidence details. what is the expression used for?

How many species of living things are alive on earth today? more than 1,000,000 none of these answers are correct 100-500 1,000 –500,000 o 500,000 -1,000,000

What type of organism is a one-celled organism that functions as a single unit? a. bi-celled b. single-celled c. pre-celled d. multi-celled