Which meaning from the dictionary best matches the underlined word as it is used in the paragraph?

three elephants were moved from a zoo to their new home in california. they had to be trained to ride in the huge hold for cargo arranged for their flight. their trip would take 10 hours instead of 40 if they'd had to be shipped by truck.

read the dictionary entry.

cargo (kahr-goh)
noun
1. the freight of a ship or plane
2. a load
3. a type of pants
adj.
4. describing a type of pants with cargo pockets
5. a type of ship

a.

1. the freight of a ship or plane

b.

2. a load

c.

3. a type of pants

d.

4. describing a type of pants with cargo pockets

the underlied word cargo