What is the transposition for a Sop/Tenor saxophone?

The correct transposition for a soprano or tenor saxophone is indeed from the key of B-flat, which means that when a soprano or tenor saxophone plays a written C, it sounds as a B-flat in concert pitch. This is typical for instruments that are in the B-flat key family. Hence, musicians need to transpose their music down a major second (which is equivalent to a whole step) to align what they are playing with the concert pitch heard by other instruments.

For instance, if they see a written C, they actually need to perform a B-flat to sound the correct pitch. This understanding is vital for musicians working in bands or ensembles, as accurate transposition ensures harmony and correct tonal alignment among various instruments.

Other options represent different transposition relationships applicable to other instruments or situations, but they do not apply to the soprano or tenor saxophone's B-flat transposition characteristic.