In (a) we have to find the distance between Ivanna's house and the school. The distance between buildings in the same town or city are in the order of several yards or a few miles. 1 milimeter and 1 centimeter are both smaller than an inch so 3mm or 3cm are not reasonable distances between two buildings. The same happens with 3 meter which is approximately 3.33 yards. The option that makes the most sense is 3km that is close to 2 miles since 1 mile is approximately 1.6 kilometers. So the answer to (a) is km.
In (b) we have to estimate the weight of a horse and we have two options 800g or 800kg. Horses can weight several hundreds and even more than a thousand pounds. Since 1 pound is approximately 453g then 800g is less than 2 pounds and it doesn't make sense. 1 kilogram is approximately 2.2 pounds so 800kg are equivalent to 800*2.20 pounds=1760 pounds. This makes more sense so the answer to (b) is kg.
In (c) we have the volume of a can of soda. 1 litre is equivalent to a 10cm side cube. Since 1 inch is 2.54 cm then a 10 cm side cube is a 4 inches side cube. A 350 litres can will be as big as 350 cubes with sides of 4 inches. That can would be massive so a 350 L can makes no sense. So in this case the mL seems to be the best option. One cubic inch is approximately 16.4 mL which means that 350 mL are equaivalent to 350/16.4=21.34 cubic inches which makes more sense. Then the answer to (c) is mL.