For most of the twentieth century, biologists assumed that genetic inheritance flowed only through DNA. The discovery of "epigenetic" modifications — chemical tags attached to DNA that influence gene expression without changing the underlying sequence — has complicated that picture. Some of these tags can be passed from parent to offspring, suggesting that inheritance is more multidimensional than once believed.
Which choice best describes the function of the second sentence in the text?
- Acheck_circle
It introduces a development that complicates the prior view and prepares the third sentence.
- B
It confirms the twentieth-century view introduced in the first sentence.
- C
It restates the first sentence using different terminology.
- D
It dismisses epigenetic modifications as unimportant.
Explanation
The second sentence introduces epigenetic tags that complicate the DNA-only picture and set up the third sentence's claim. B captures this transitional function.