The key to the question is to consider what is the main idea of the passage even though many of the answer choices might accurately express one of the ideas expressed in the passage. What is the author trying to argue?
Let's consider (A) & (B)
(A) is actually not supported by the passage. Lines 34-37 and 49-57 suggest that there are some benefits in releasing genetically modified bacteria into the environment, but it still requires great care, and we cannot conclusively say that it would not involve any significant danger in any scenario.
(B) accurately summarizes the author's optimism for this research (lines 56-59) and acknowledges the opponents' perspective ((lines 38-40 & 53-56).
