What is the correct order of reactivity of alkyl halides towards dehydrohalogenation?

Identify the correct decreasing order of ease of dehydrohalogenation of alkyl halides.

Observe the following reactions. The order of reactivity of $x, y, z$ towards $S_{N}1$ reaction is:

Consider the following reaction sequence:
$Cyclohexylidene-methane$ $\xrightarrow[CH_3OH]{Br_2} A$ $\xrightarrow{KCN} B$
Identify the correct structures for $A$ and $B$ from the given options:
$A$ is:
$A) \text{ 1-(bromomethyl)-1-methoxycyclohexane}$
$B) \text{ 1-(methoxymethyl)-1-bromocyclohexane}$
$B$ is:
$C) \text{ 1-(bromomethyl)-1-methoxycyclohexane}$
$D) \text{ 1-(cyanomethyl)-1-methoxycyclohexane}$

Predict the major product for the following $E2$ elimination reaction:

Formation of $2-$butene from $2-$bromobutane is according to