If some B are C and all C are D, which statement about B and D is true?

If some B are C and all C are D, which statement about B and D is true?

• A. All B are D
• B. No B are D
• C. Some B are D
• D. All D are B

Answer: (C)

The idea is layering a couple of statements to see what must be true. If some things are B and C, and every C is D, then that B–C thing is also a D. Since there exists at least one item that is both B and C, that same item is D as well. So there must be at least some B that are D. That makes the conclusion “Some B are D” the only guaranteed one. It doesn’t force all B to be D, because B could include things that aren’t C and thus aren’t necessarily D. It also doesn’t rule out B and D overlapping overall or require that all D are B. So the correct takeaway is: some B are D.

The idea is layering a couple of statements to see what must be true. If some things are B and C, and every C is D, then that B–C thing is also a D. Since there exists at least one item that is both B and C, that same item is D as well. So there must be at least some B that are D.

That makes the conclusion “Some B are D” the only guaranteed one. It doesn’t force all B to be D, because B could include things that aren’t C and thus aren’t necessarily D. It also doesn’t rule out B and D overlapping overall or require that all D are B. So the correct takeaway is: some B are D.