The type of cargo carried on the Magdalena and Cauca rivers is:

It is given in the question that

Malaya creates a password as follows:

letter, number, letter, special character, number

For the letter, we have 26 options. For numbers , we have 10 options. And it is given that, for special character, we need to use 12.

So the most guesses you have to make is

So the correct option is b.