instead of bc547 for amplfier which transistor i can use out of BD137,BC557,2N3904,1C128

 

Four widely varied transistor types presented as possible alternatives? The last type (1C128) does not seem to be listed as a BJT, perhaps it should be AC128?

This looks like a homework multiple choice question, so perhaps it would be better if you tried to find the datasheets on the web for yourself.

 

instead of bc547 for amplfier which transistor i can use out of BD137,BC557,2N3904,1C128

Hi bc547 is an NPN BD137 is a bigger transistor (no),bc557 is a PNP (no), 2n3904 is an equivalent(yes) I do not know 1C128.