The point is not just about specific time; it's about the use of what we call the pseudo-passive. There are some verbs that are used in the active voice, but really represent the passive voice in how they're used. This is a great example. Merchandise doesn't sell anything -- people do that. But it's very typical to use the verb sell as a pseudo-passive, as we see in choice d above.
Another example is the verb weigh: This turkey weighs 16 lbs.
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