question $3$ is wrong $-$ please help $--$ the choses are

Susan $-$ accounting analysis method $,$ high low method or regression method

Gary $-$ Your answer is partially correct.

Susan and Gary met with the supervisor of the pizza division of a medium$-$sized Italian food supplier. The supervisor explained the two key costs in his division, as follows.

Although Susan and Gary used this data to estimate a model for the division's costs, they each came up with a different model, as follows.

Susan's cost model $,$ Total pizza division cost $=$$$3\mathrm{.}90($number of pizzas$)+$$$5,865$

Gary's cost model Total pizza division cost $=$$$5\mathrm{.}60($number of pizzas$)$

What understanding did Susan have about the cost behavior of these costs?

MOH cost

Pizza cost

What understanding did Gary have about the cost behavior of these two costs?

MOH cost

Pizza costaccounting analysis method $,$ high low method or regression method