This tells us that a thing’s being required to solve a problem is necessary in order for it to be something we should adopt. But (A) doesn’t establish that we actually should do the thing. (A) would be correct if it had started with “If” rather than “Only if.”

We are not told about a measure that’s sufficient to solve a problem. We know what’s required to solve homelessness — government building housing and taxation. But we don’t know these are sufficient. (B) also doesn’t help reach the conclusion that something should be adopted.

This helps connect the premises to the conclusion. We know increased taxation is necessary to solve homelessness. Based on (C), we can then conclude that we should increase taxation.

We are not told about any measure that’s sufficient to solve the problem of homelessness. We know what’s required to solve it — government building housing and taxation. But we don’t know these are sufficient to solve homelessness.

We are not told about any measure that’s sufficient to solve the problem of homelessness. We know what’s required to solve it — government building housing and taxation. But we don’t know these are sufficient to solve homelessness.