Suppose in 1980 nominal GDP in country F was equal to $500 and in 2000 was equal to $2400. The GDP deflator was 100 and 500, respectively. Which one is true:

Question

Suppose in 1980 nominal GDP in country F was equal to $500 and in 2000 was equal to $2400. The GDP deflator was 100 and 500, respectively. Which one is true:
a) Country F in 2000 was richer, in real terms, than in 1980
b)prices have increased faster than nominal GDP
c)there has been an annual rate of inflation of 1%
d)real GDP has remained unchanged

i think its between b or c, please help.