Assertion–Reason (Vehicular emissions as an environmental concern) Assertion (A): Vehicular emissions are a cause of concern for environmentalists. Reason (R1): Emissions contain several gases and particulates that are harmful to human health. Reason (R2): In cities, emission levels from vehicles can be very high. Select which reason(s) truly explain A.

Introduction / Context:Environmental concern around transport arises from toxicity and scale. This item asks whether toxicity (R1) and elevated urban levels (R2) together justify the assertion (A).

Given Data / Assumptions:

• A: Vehicular emissions are concerning.
• R1: Composition includes harmful gases/particulates.
• R2: Urban emission levels often become high (density of vehicles, congestion patterns).

Concept / Approach:Risk = hazard × exposure. R1 states the hazard; R2 describes higher exposure contexts. Both combine to elevate risk and justify the concern in A.

Step-by-Step Solution:

Verification / Alternative check:Health studies link traffic emissions to cardiopulmonary morbidity; urban peaks are consistently documented—aligning with R1 and R2.

Why Other Options Are Wrong:A or B alone under-explain; D ignores both hazard and exposure.

Common Pitfalls:Forgetting that concern rises with both danger and dose.

Final Answer:If both (R1) and (R2) are reasons for the assertion (A).