The correct option is
D c-i, a-ii, e-iii, b-iv, f-v, d-vi
Walrus - A large Arctic (Polar) marine animal characterized by tusks and whiskers.
Cedar - A softwood tree with its wood being stable, finely textured and extremely long lasting.
Olives - A citrus fruit grown majorly in Mediterranean basin and Africa.
Elephants - In South Asia they dwell in tropical deciduous forests. In Africa they are also found in tropical rain-forests.
Campos - Grassland covers parts of Brazil, Paraguay and Argentina, and all of Uruguay.
Downs - Grassland covers mostly Northern Australia. These are vast plains of tall, dense grass with pockets of woodlands.