Burden of current transformer is usually expressed in

A. Amperes
B. Volts
C. Volt amperes
D. Kilowatt

Answer: C. Volt amperes

Explanation::
Current Transformer​:

• A Current Transformer (CT) is used to measure the current of another circuit.
• CTs are used worldwide to monitor high-voltage lines across national power grids.
• Load on Current Transformer is called as a burden because Current Transformer secondary winding can’t be kept open, high voltage can do the insulation failure.
• So it is necessary to load the Current Transformer secondary winding continuously and ultimately it acts as a burden on the Current Transformer.
• The burden of the Current Transformer can be specified as Volt-Ampere absorbed at a certain Power Factor.
• The burden of a current transformer is the value of the load connected across the secondary transformer. 
• It is expressed as the output in volt-amperes (VA). 
• The rated burden is the value of the burden on the nameplate of the CT. 
• The rated burden is the product of the voltage and current on the secondary when the  CT supplies the instrument or relay with its maximum rated value of current.