If some B are C and all C are D, which conclusion about B and D is correct?

If some B are C and all C are D, which conclusion about B and D is correct?

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

Answer: (A)

This question tests how to combine statements about groups using “some” and “all.” If some B are C, there’s at least one thing that is both B and C. If all C are D, every C is also D. So that same thing, which is in C, must be in D as well. Therefore there exists something that is both B and D—i.e., some B are D. The other possibilities aren’t guaranteed by the given information. All B are D would require every B to be in D, but we only know the B that overlaps with C is in D, not every B. No B are D would contradict the existence of a B that is in D. All D are B would require D to be entirely within B, which isn’t implied by C being a subset of D and some B overlapping with C.

This question tests how to combine statements about groups using “some” and “all.” If some B are C, there’s at least one thing that is both B and C. If all C are D, every C is also D. So that same thing, which is in C, must be in D as well. Therefore there exists something that is both B and D—i.e., some B are D.

The other possibilities aren’t guaranteed by the given information. All B are D would require every B to be in D, but we only know the B that overlaps with C is in D, not every B. No B are D would contradict the existence of a B that is in D. All D are B would require D to be entirely within B, which isn’t implied by C being a subset of D and some B overlapping with C.