Please refer to the equation given below to answer the following questions:

Assume that all other variables in the equation do not change

${}_L={}_u(1+(1-t)(\frac{D}{E}))$

where

$L=$ Levered Beta for equity in the firm

${}_u=$ Unlevered beta of the firm $($i$.$e$.,$ the beta of the firm without any debt$)$

$t=$ Corporate tax rate

$\frac{D}{E}=$ Debt$/$Equity Ratio

$16.$ An increase in the Debt results in

a$.$ An increase in growth rate

b$.$ An increase in cost of equity

c$.$ A decrease in cost of equity

d$.$ An increase in firm value

e$.$ None of the above

$17.$ An increase in the equity results in

a$.$ An increase in growth rate

b$.$ An increase in cost of equity

c$.$ A decrease in cost of equity

d$.$ An increase in firm value

e$.$ None of the above

$18.$ An increase in tax rate results in

a$.$ An increase in growth rate

b$.$ An increase in cost of equity

c$.$ A decrease in cost of equity

d$.$ An increase in firm value

e$.$ None of the above

$19.$ An increase in unleveraged beta results in

a$.$ An increase in growth rate

b$.$ An increase in cost of equity

c$.$ A decrease in cost of equity

d$.$ An increase in firm value

e$.$ None of the above