Event A: Curfew has been declared in the city. Event B: There is hardly any…

Concept: In cause-and-effect reasoning, the immediate and principal cause is the event that occurs first and directly, necessarily produces the other event, with no independent factor needed in between; the effect could not occur in that way without the cause.

Application: Event A — the declaration of a curfew — is an administrative order issued first. Event B — the near-total absence of visible activity and the closing of shops — follows directly and necessarily from that order, since a curfew explicitly restricts people from stepping outdoors and businesses from operating. No intervening cause is required to connect the two: once the curfew takes effect, the conditions described in B follow immediately.

Cross-check — why the other readings fail:

• Reversing the direction (treating low street activity as producing the curfew) does not hold: a curfew is an administrative order issued by authorities, and public inactivity is not a cause of that order.

• Reading B as an effect but denying A as its immediate cause fails because no independent, intervening factor is needed — the curfew alone directly explains the described conditions.

• Reading A as an effect misreads its role: the curfew is the originating action here, not a consequence of anything stated in the two events.

Result: the curfew (A) is the immediate and principal cause, and the absence of visible activity (B) is its direct effect.