Wrong flaw. This assumes that an effective treatment becomes more effective when administered in greater quantity. The stimulus doesn’t assume that increasing the dose of copper would increase its effectiveness—it makes an assumption about what causes late blight.

No flaw. This proposes a cure for a condition that directly addresses its known cause. If scurvy is caused by a lack of vitamin C, then it’s reasonable to conclude that supplying that nutrient would effectively treat it.

Wrong flaw. This assumes that supplying more of a missing component is always better, ignoring possible negative effects (like weight gain). But the original argument doesn’t assume more copper equals more benefit—it wrongly assumes that copper cures late blight because it makes up for a deficiency.

This assumes that if something (paracetamol) effectively treats a condition (headaches), it must do so by replacing a missing component. It’s possible that paracetamol is effective for entirely different reasons.

Wrong flaw. This mistakes a sufficient condition for a necessary one. There may be conditions other than a calcium deficiency that cause brown spots on apples. The stimulus is flawed in that it assumes a treatment is effective because it makes up for a deficiency.