Answer :
The stringed instruments enter in the order of cello followed by violin, based on the given information about the piece. The excerpts mention the cello playing the A strain initially and then the violin entering with pizzicato and later with a variation on the B strain. Thus, the correct answer is c. cello, followed by violin.
The order in which the stringed instruments enter in the piece can be deduced from the provided information. The cello begins with the A strain, as indicated by the fact that 'the cello plays the A strain', and the accompaniment is provided by piano and pizzicato violin, which implies that the violin enters after the cello. Furthermore, it mentions that the violin and cello repeat their joint material, indicating that the violin enters after the cello at some point. Additionally, there is a moment where 'the two violinists play a variation on the B strain' which shows an instance when the violins are playing, possibly after the cello.
Given the information, it seems that the order is: cello, followed by the violin. The viola is not specifically mentioned in the excerpts provided, making it less clear when it enters in relation to the cello and violin. Therefore, based on the provided details, the answer is cello followed by violin. Thus, the correct answer is c. cello, followed by violin.
