Homework question on identifying a key from a V triad

Question

I am working through the ABRSM Discovering Music Theory Grade 4 book. I appear to have found an unanswerable question, unless I have misunderstood something. It's Section 7, Exercise 3, question k, on page 49 of the book.

Section 7 is about the tonic (I), subdominant (IV) and dominant (V) triads of the different keys. Exercise 3 has the reader identifying the key (including major or minor), given one or more of those triads.

Question k gives only the V triad. It is A, C#, E. So it must be a D key. If it's D major, then the C should be sharped, and it is. If it's D minor, then the 7th should be raised a semitone, which makes the C a C#, which it is.

Am I missing something, or is the V triad of D major the same as the V triad of D minor?

Answer 1

You are correct. It can be both D major and D minor. I know this may be a bit unsatisfying, but I verified the answer by looking at the answer book for your textbook. Nice catch!

Answer 2

The V of any key will be major (with M3). It's often the case with minor keys - it makes a proper leading note, one semitone below the tonic. If, in key Dm, the C is C♮, then it would be represented in RN as v. That's not really in the remit of grade IV, for that question.

So the answer could be either - although if it's D minor, iv (not IV) will have to be G minor.