The fixed skeleton (works for every question).
Seven episodes fill Weeks 1–7, one per week. Line up the ordering rules:
- Basalt before Ember; Ember before Glade.
- Basalt before Dune, Cedar before Dune; Dune before Frost; Frost before Glade.
- Harbor is Week 1.
From these:
- Harbor = Week 1 (given outright).
- Glade = Week 7. Glade sits at the end of both chains (Basalt → Ember → Glade and Basalt/Cedar → Dune → Frost → Glade), so nothing can come after it — it must be last.
- Week 2 must be Basalt or Cedar. Every other episode has something that must come before it (Ember needs Basalt; Dune needs Basalt and Cedar; Frost needs Dune; Glade needs everything). Only Basalt and Cedar have just Harbor ahead of them, so one of them takes the first open slot.
- Dune ≥ Week 4. Dune must follow Harbor, Basalt and Cedar — three episodes — so the earliest it can land is Week 4.
- Frost ≥ Week 5. Frost follows Dune, so it is at least one week later than Dune's earliest, i.e. Week 5.
- Ember ≤ Week 6, since Ember must come before Glade (Week 7).
| Week | 1 | 2 | 3 – 6 | 7 |
|---|
| Episode | Harbor (fixed) | Basalt or Cedar | Basalt/Cedar, Dune, Ember, Frost — within their bounds | Glade (fixed) |
Bounds to remember: Dune ≥ Wk 4, Frost ≥ Wk 5, Ember ≤ Wk 6.
This question — which CANNOT be true?
- (A) Dune in Week 3 — impossible: Dune needs Harbor, Basalt and Cedar all before it, so it can be no earlier than Week 4.
- (B) Cedar in Week 4 — possible, e.g. Harbor, Basalt, Ember, Cedar, Dune, Frost, Glade.
- (C) Ember in Week 6 — possible, e.g. Harbor, Basalt, Cedar, Dune, Frost, Ember, Glade.
- (D) Frost in Week 5 — possible (that same order has Frost in Week 5).
Only (A) breaks a rule.
Answer: Dune was released in Week 3 (option A)
💡 Teacher tip: For a "cannot be true" question, count how many episodes are forced to sit before the one in the option. Dune has three mandatory predecessors, so Week 3 is out before you check anything else.