a. Increase in indirect tax - this raises inflation as it is first felt by suppliers who generally opt to pass on these increases in cost of production as higher prices, creating cost inflation.
b. depreciation AUD - generally makes necessary imported inputs more difficult to obtain for Australian business, reduces technial efficiency and AS - upwards pressure on prices meaning cost inflation.
c. an increase in labour productivity - means given labour inputs are being used for efficiently, producing more. Increase in AS less cost inflation.
d. increase in energy costs - same as the first one -increase in cost inflation.
So, A,B and D all increase cost inflation, meaning C is the only logical answer.
Hope it is helpful