Assertion–Reason (Opposite Seasons by Hemisphere):\nAssertion (A): In December, Britain has winter while Australia has summer.\nReason (R): Australia is located in the Southern Hemisphere.

Introduction / Context:
This Assertion–Reason item tests basic Earth–Sun geometry and the climatic consequence of hemispheric tilt. Learners must judge the truth of both statements and then evaluate whether the Reason causally explains the Assertion.

Given Data / Assumptions:

• A: December brings winter to Britain and summer to Australia.
• R: Australia lies in the Southern Hemisphere.
• Earth’s axis is tilted (~23.5 degrees) relative to its orbital plane; seasons arise from changing solar declination, not from Earth–Sun distance.

Concept / Approach:
The hemisphere tilted toward the Sun receives higher solar altitude and longer daylight, producing summer conditions. The opposite hemisphere has lower solar altitude, shorter days, and thus winter.

Step-by-Step Solution:
1) Truth of A: Britain is in the Northern Hemisphere; December is boreal winter. Australia is in the Southern Hemisphere; December is austral summer. So A is true.2) Truth of R: Australia is unequivocally south of the equator; R is true.3) Explanatory link: The hemispheric location (Southern vs Northern) combined with axial tilt directly explains the opposite seasons observed in December. Hence R correctly explains A.

Verification / Alternative check:
Check solstice dates: Around December 21–22 is the Southern Hemisphere’s summer solstice and the Northern Hemisphere’s winter solstice, matching the assertion.

Why Other Options Are Wrong:
(b) denies the correct explanation; (c) incorrectly calls R false; (d) wrongly negates A; “None” is unnecessary.

Common Pitfalls:
Attributing seasons to Earth–Sun distance (perihelion/aphelion) rather than axial tilt and solar angle/day length.

Final Answer:
Both A and R are true, and R correctly explains A.