Usually in your talks with co-workers you :

The answer is D (smile at the correct time). This is a behavioural or situational item rather than a factual one, so the test is which option reflects calibrated, context-sensitive social conduct. Smiling at the right moment shows you are reading the conversation and responding to it, which is what emotional intelligence means in practice.

• A (grave): Constant seriousness makes a colleague's conversation stiff and signals detachment. It fails the basic test of workplace rapport.
• B (always smiling): A fixed expression ignores context. Smiling during a serious discussion or a complaint looks insincere or tone-deaf.
• C (smiling in support of their views): This ties your expression to agreement rather than to the moment. It hints at sycophancy, which an administrator must avoid when a colleague's view is wrong.

The concept is social and emotional competence, which links to the Ethics paper (GS IV) on emotional intelligence and to Mains answers on administrative behaviour and teamwork.

Trap: Aspirants pick B because smiling sounds positive. The question is about appropriateness, not frequency.