Read the passage given below and fill in the blanks by choosing the most appropriate options from the ones that follow:
Alaska's size and climate make transportation (a) - challenge. Long ago, sledges pulled (b) - dog teams were the best way to travel (c) - native people.
(a) (i) an (ii) the (iii) a (iv) for
(b) by (ii) with (iii) of (iv) beside
(c) (i) by (ii) to (iii) for liv) with