A multiproduct firm's cost function was recently estimated as:

$C(Q_1,Q_2)=90-0\mathrm{.}5Q_1{Q}_2+0\mathrm{.}4Q_1^2+0\mathrm{.}3Q_2^2$

a$.$ Are there economies of scope in producing $10$ units of product $1$ and $10$ units of product $2?$

No $-$ there are no economies of scope.

You cannot determine if there are economies of scope.

Yes $-$ there are economies of scope.

b$.$ Are there cost complementarities in producing products $1$ and $2?$

No $-$ there are no cost complementarities.

You cannot determine if there are cost complementarities.

Yes $-$ there are cost complementarities.

c$.$ Suppose the division selling product $2$ is floundering and another company has made an offer to buy the exclusive rights to produ product $2.$ How would the sale of the rights to produce product $2$ change the firm's marginal cost of producing product $1?$

Marginal cost would not change.

Marginal cost would increase.

Marginal cost would decrease.