For the chemical reactions shown below,identify the correct statement from the following:

Predict the major product $A$ for the following reaction:
$2\text{-methylbuta-1,3-diene} + HBr (1 \text{ eq.}) \xrightarrow{-80^{\circ}C (1,2\text{-addition})} A$

Propanal and pentan-$3$-one are the ozonolysis products of an alkene. What is the structural formula of the alkene?

Which of the following alkenes reacts fastest with $H_2$ under catalytic hydrogenation conditions?

Bayer's reagent used to detect olefinic double bond is

An alkene $(A)$ $C_{16}H_{16}$ on ozonolysis gives only one product $(B)$ $C_8H_8O$. $(B)$ can also be obtained by the hydrolysis of the product obtained from the reaction between cyanobenzene and $CH_3MgBr$. $(A)$ shows geometrical isomerism and decolourises $Br_2$ water. $(B)$ on treatment with $SeO_2$ produces $(C)$. Which statement is not correct about $(A)$?