All of the following are examples of source reduction except using canvas shopping bags using paper, rather than plastic, shopping bags composting recycling

i think it is recycling since it does not reduce sources.

using paper, rather than plastic, shopping bags. I got the answer right on my test. This is because your still using a bag non the less so you still are using a source being a bag.

in situ hybridization has been widely used for research applications, including clinical cytogenetics, gene mapping, tumor biology and studies of chromosome evolution.