A biologist formulates a hypothesis, performs experiments to test his hypothesis, makes careful observations, and keeps accurate records of his findings. In order to complete this process, the biologist should

A) adjust the data to support the hypothesis
B) eliminate data that do not support the hypothesis
C) write a research paper explaining his theories before performing his experiments, in order to gain funding sources
D) evaluate the findings and, if necessary, alter the hypothesis based on his findings, and test the new hypothesis