An abstract usually contains one or two key sentences from each section of a paper. Read the following extract from somebody's draft abstract. Match a section to the extract.

Current surface conditions on Mars are extremely challenging for life. However, Nicholson and Schuerger (2005) reported that Bacillus subtilis was able to survive for 19 days under Mars atmospheric pressure and composition. The question is whether there are any features on Mars that could provide protection against the surface conditions. One possibility is that the surface material plays a protective role due to the fact that it is composed of iron oxides and hydroxides.