Surviving seventeenth-century Dutch landscapes attributed to major artists now equal in number those attributed to minor ones. But since in the seventeenth century many prolific minor artists made a living supplying the voracious market for Dutch landscapes, while only a handful of major artists painted in the genre, many attributions of seventeenth-century Dutch landscape paintings to major artists are undoubtedly erroneous. Which one of the following, if true, most strengthens the argument? ['More seventeenth-century Dutch landscapes were painted than have actually survived, and that is true of those executed by minor artists as well as of those executed by major artists.', 'In the eighteenth century, landscapes by minor seventeenth-century artists were often simply thrown away or else destroyed through improper storage.', 'Technically gifted seventeenth-century Dutch landscape artists developed recognizable styles that were difficult to imitate.', 'Seventeenth-century art dealers paid minor artists extra money to leave their landscapes unsigned so that the dealers could add phony signatures and pass such works off as valuable paintings.']