Figure 6 shows the urine test results of four athletes. Describe the evidence in Figure 6 that shows the test for athlete B has not worked. Suggest one reason why the test did not work.

**Evidence:** The test for athlete B is invalid because the control line (the top line) has not turned blue. A blue control line must appear for any test to be considered valid, as it confirms the test strip is working and the sample has flowed correctly up the strip. Since it is missing for athlete B, the result cannot be trusted. **Reason:** A possible reason for the test failing is that an insufficient amount of urine was added to the test strip. If there wasn't enough liquid, it would not have been able to flow all the way up to the control area to activate it. Another possibility is that the test strip itself was faulty.