We are told that we want a triangle of area 56. Recall that the area of a triangle of base b and height h is given by the formula

In our case we want

now, we want to find an expression for b. We are told that the base is one less than twice the height. That is, we take the height, multiply it by 2, and then subtract 1. That would lead to

so we have

so the second option is correct.