A Year Ago a Country Reduced the Tax Rate on All

A year ago a country reduced the tax rate on all interest income from 40% to 10%. During the year private saving was $600 billion as compared to $500 billion the year before the tax reform. Taxes collected on interest income fell by $150 billion. Assuming no other changes in government revenues or spending which of the following is correct?

A) The substitution effect was larger than the income effect; national saving rose
B) The substitution effect was larger than the income effect; national saving fell
C) The income effect was larger than the substitution effect; national saving rose
D) The income effect was larger than the substitution effect; national saving fell