Multi-choice problem: Continue writing the next sentence in this paragraph:

How to make glow sticks glow again
Find a little extra light.
Crack the glow stick down every bit of its length. If no light at all appears, your glow stick is completely used up and there's no hope for it.

pick from the following.
[a]. Measure and cut a length of wire or string. Adding a bit more (or less) to the end of the wire is also optional.;
[b]. If you can get a tiny bit of light, even just a couple spots, you've got something to work with. The light in a glow stick is caused by a reaction between two chemicals.;
[c]. You can use colored glow sticks, but be warned that they don't glow the most and are probably overused. A cheap glow stick that can be bought at most craft stores is a good starting point.;
[d]. Place some glow sticks on, one of the glow sticks facing up. Grab another glow stick, and place it on top of the first one that was totally used up.;
[b].