How do you help a student who will not try?

Today was an end-of-nine-weeks testing day for my 5th graders. Their test (provided by the school) was a little easy for my standards (and STAAR standards!), but I was actually a little relieved since they have state testing coming up. I thought they could use a little confidence booster. However, I was really, really sad when I had students turning in this test, that I thought was on the easy side, with answers that did not make sense! For example, look at this question.

The students LITERALLY have to just write down the formula for volume. We spent 4 days on volume in our class. By the end of that week, those kids were eating, sleeping, and breathing volume. Not to mention each student is given a reference sheet that gives the formula for volume! I still had at least 15 out of my 75 students get that question incorrect. Some of them I caught as they were turning it in, but some I did not catch. I don't understand how they can be getting this extremely simple, knowledge level (Bloom's) question incorrect! I'm really bummed. So now to my question: what can I do for them? There is no way I could have drilled into their heads more the formula for volume. But, in any case, they were GIVEN the information. I have no clue how to get them to care enough to just find the answer. I'm very frustrated. I have such smart students and I work very hard to teach them, but I still end up with these low grades and little (sometimes no) effort shown for a large percentage of my class. Is this just a necessary evil of teaching, or can I do something to help them. I have been trying to motivate them all year and I am getting basically nowhere with some of them. I'm especially worried since they must pass the STAAR (state testing) this year to go to 6th grade. HELP!