Take this into account:
1) Decrease every three months => 12 / 3 = 4 => 4 times is a year
2) Increase every four months => 12 / 4 = 3 => 3 times in a year
3) Decrease of 5% => rate = 0.95
4) Increse of 12% => rate = 12%.
With that the answer comes easily: expression A decays at a rate of 5% every 3 months, while expression B grows at a rate of 12% every four months.