Argument: 'The parcel was sent out from the warehouse on Tuesday morning, so it reached the branch on Wednesday.' The conclusion follows logically if which of the following is assumed?

The argument runs forward from despatch to arrival, so it needs a guarantee running that same way and covering every such parcel — which is what the third option states. 'Usually' allows this parcel to be the exception, so the conclusion would not be secured. The first and fourth options both run backwards, from a Wednesday arrival to a Tuesday despatch, and neither tells us anything about a parcel we know only to have been sent out.