Of the options, we have, "clean up after your animals", is a sentence that doesn't make much sense, cleaning up, certainly is helpful but it doesn't make a great difference, although some consider it good practice for avoiding further contamination of drains. Taking into account this, option four "all of the above" is not a proper answer unless you consider this as a good practice, but as said, it doesn't make a great difference. Now proper disposal of chemicals can make a big difference, an example is the pollution generated by textile factories or mining if its waste is properly managed their impact can decrease considerably. The other option "reduce the use of plastic", is also a good option, as we know now, the rupture of plastic waste generates microplastics, which are a huge ecosystem problem, as well as a public health problem.