Chemical bonds that involve the total transfer of electrons from one atom or group of atoms to another are called a. covalen bonds b. ionic bonds c. hydrogen bonds d. van der waals bonds

i believe the correct answer from the choices listed above is the first option. the scientists need to look at the   validity of data, claims, hypotheses, and observations before  developing an argument. they base their arguments on facts that are present and they make sure they have proofs. 

explanation:

thymine. in rna, thymine is replace by uracil