MYTS 2018 — Grade 5 — Round 1 Question 15

Gifts are prepared for Lan, Hương, Thúy and Quỳnh. Exactly one of them opens the boxes. They say:
- Lan: Hương did not open them.
- Hương: Lan or Quỳnh did.
- Thúy: Hương did.
- Quỳnh: Lan or Thúy did.
Exactly one person lies. Who opened the gifts?