Forward rate and spot rate

The spot exchange rate for United States dollars per United Kingdom pound (USD/GBP) is 1.5775. If 30-day interest rates are 1.5% in the United States and 2.5% in the United Kingdom, and interest rate parity holds, the 30-day forward USD/GBP exchange rate should be:
A 1.5621
B 1.5762
C 1.5788

Plz help me solving this

Assuming nominal rates and a 360-day year:

USD/GBP\ 1.5775 = \frac{USD\ 1.5775}{GBP\ 1.0}
\frac{USD\ 1.5775}{GBP\ 1.0}\left[\frac{1 + 0.015\left(\frac{30}{360}\right)}{1 + 0.025\left(\frac{30}{360}\right)}\right]
= \frac{USD\ 1.579472}{GBP\ 1.002083} = \frac{USD\ 1.5762}{GBP\ 1.0}\ =\ USD/GBP\ 1.5762

Thanks @S2000magician

My pleasure.