All other issues are __________ to the need to provide food and medical supplies.

The tone of the sentence suggests that the "need to provide food and medical supplies" is more important than any other.

Option A: This word relates to subsistence, meaning barely surviving or self-sustaining. It doesn’t fit the context of prioritizing issues.

Option B: This is a geometric term meaning to extend under or opposite to (e.g., an angle or arc). It’s not relevant here

Option C: This means to include or absorb something into a larger category. While it might seem close, it doesn’t convey the sense of priority needed in the sentence. 

Option D: "Subsidiary" means secondary or less important in relation to something else. This will provide the required meaning to the sentence.

Hence, the answer is option D.