Suppose aggregate output is demand$-$determined. Suppose a decrease in autonomous investment expenditure of $$20$ million reduces equilibrium national income by $$48$ million. The marginal propensity to spend is equal to

A$.2\mathrm{.}40.$

B$.0\mathrm{.}58.$

C$.0\mathrm{.}42.$

D$.-2\mathrm{.}40,$

E$.-0\mathrm{.}58.$