Mr. and Mrs. Tan have four children--three boys and a girl--
who each like one of the colors--blue, green, red, yellow--
and one of the letters--P, Q, R, S.
- The oldest child likes the letter Q.
- The youngest child likes green.
- Alfred likes the letter S.
- Brenda has an older brother who likes R.
- The one who likes blue isn't the oldest.
- The one who likes red likes the letter P.
- Charles likes yellow.
Based on the above facts, Darius is the __________.