Final answer:
The correct synonym for 'trifle' as a noun is 'little', referring to something of small significance or value.
Step-by-step explanation:
The word 'trifle' as a noun refers to something of little value or importance. Among the options provided, the synonym for 'trifle' is b) Little. This is because 'little' can also refer to something small or of low significance, which is in line with the meaning of 'trifle'. The other options do not accurately reflect the meaning of 'trifle' as a noun since a 'streamlet' is a small stream, 'tax' pertains to a compulsory contribution to state revenue, and 'guile' means sly or cunning intelligence.