[单选题]
3. Which of the following are regarded as possb w9cjw;k b6,ar-ibu1ible causes of mutations in DNA?
a7,azjlc1ne5 0 1 bfpf I. Errors in DNA replication.
II. Mutagenic chemicals.
III. Advantageous traits in a parent.
IV. Some forms of radiation.
A. I and II only
B. II and IV only
C. I and III only
D. I, II and IV only