Question

why do tree on Hill have sloping branches

Answer 1

because this don't allow snow to stay on the leaves

Answer 2

As there is too much snowfall on the Hills, the trees have sloping branches. So that the snow slips down the branches and does not remain on the branches because if it remains on the branches the branches may break due to the weight of the sun or the sunlight would not be able to reach due to the snow.