Ellipse single-correct with parametric depth
Knowledge bridge
Step 1: place the ellipse in standard form and introduce eccentric angle or slope form. Step 2: impose the geometric condition (tangent/chord/focus). Step 3: match the simplified relation to the correct option.
Why it feels hard
Parametric slips create attractive wrong options.
What to practise
Keep both slope and parametric forms of ellipse tangents fluent.