[单选题]
3. Which of the following a( krp; 1n6tfzu k:8tbere h0q:ztku;ac:pv(k8 pz 7skh*regarded as possible causes of mutations in DNA?
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