Passage Summary: Old people often have high blood pressure because they lack calcium, and since milk is full of calcium, drinking it should help lower their pressure.

Conclusion: Some elderly people can reduce their blood pressure by consuming milk.

Reasoning: High blood pressure in seniors is often linked to calcium deficiency, and a single glass of milk contains enough calcium to correct such a deficiency.

Analysis: The argument contains a 'gap' regarding the absorption of calcium. The premises mention that the deficiency is often caused by a lack of Vitamin D, which is required for the body to actually use the calcium. For the conclusion to be guaranteed, we must assume that the people drinking the milk are actually able to absorb the calcium it provides. Look for an assumption that addresses this biological hurdle.