下面这个道题完全看不懂，GWD4-14，哪位好心人帮忙解释一下。

Which of the flowing most logically
completes the argument?

The attribution of the choral work Lacrimae
to the composer Pescard (1400 – 1474) has been regarded as tentative, since it
was based on a single treatise from the early 1500’s that named Pescard as the
composer.  Recently, several musical
treatises from the late 1500’s have come to light, all of which name Pescard as
the composer of Lacrimae. 
Unfortunately, these newly discovered treatises lend no support to the
attribution of Lacrimae to Pescard, since _______.

        
1. the treatise from the early 1500’s misidentifies the composers
        of some of the musical works it considers

        
2. the author of the treatise from the early 1500’s had no very
        strong evidence on which to base the identification of Pescard as the
        composer of Lacrimae

        
3. there are works that can conclusively be attributed to Pescard
        that are not even mentioned in the treatise from the early 1500’s

        
4. the later treatises probably had no source for their
        attribution other than the earlier treatise

        
5. no known treatises from the 1600’s identify Pescard as the
        composer of Lacrimae