Tackle this by ranking the drugs by trial evidence. Heavy menstrual bleeding has a well-studied medical ladder, and the question wants the agent that fails the evidence test.
The proven performers are clear. Tranexamic acid blocks fibrinolysis in the endometrium and reliably cuts measured menstrual blood loss in randomised studies. Combined oral contraceptive pills stabilise and lighten the cycle and are an accepted first-line option. Progestogens, whether cyclical oral progesterone or, more powerfully, the levonorgestrel-releasing intrauterine system, thin the lining and substantially reduce flow. Each of these has solid supporting data.
Ethamsylate is the weak link. Although marketed as a capillary-acting hemostatic, the controlled evidence shows it produces little or no meaningful reduction in menstrual blood loss, so guidelines do not regard it as an effective, evidence-based treatment for menorrhagia.
By elimination, the non-evidence-based choice stands out.
\[\boxed{\text{Ethamsylate}}\]