What will be $A$,$B$,$C$,and $D$ in the following reaction sequence?
Cyclohexanol $\xrightarrow[H_2SO_4]{CrO_3} A$ $\xrightarrow[(ii) H_3O^+]{(i) CH_3MgI} B$ $\xrightarrow{\Delta, H_2SO_4} C$ $\xrightarrow[(ii) H_2O_2, NaOH]{(i) (BH_3)_2} D$

(A) The reaction sequence is as follows:
$1$. Cyclohexanol is oxidized by $CrO_3$ in $H_2SO_4$ (Jones reagent) to form Cyclohexanone $(A)$.
$2$. Cyclohexanone reacts with $CH_3MgI$ followed by acid hydrolysis to form $1-$methylcyclohexanol $(B)$.
$3$. $1-$methylcyclohexanol undergoes acid-catalyzed dehydration with $H_2SO_4$ and heat to form $1-$methylcyclohexene $(C)$.
$4$. $1-$methylcyclohexene undergoes hydroboration-oxidation with $(BH_3)_2$ followed by $H_2O_2/NaOH$ to form $2-$methylcyclohexanol $(D)$.