What is the product of Hydroboration-oxidation of but-$1$-ene?

$CH_3-CH=CH_2 \xrightarrow[{(low \, conc.)}]{Br_2/h\nu} (A)$; Product $(A)$ of the reaction is

Product $(A)$ will be

Which reaction has the lowest $\Delta G^{\ddagger}$ (Activation Energy)?

Which of the following compounds does not follow the Markovnikov rule when reacting with $HBr$?

$Br-CH_2-CH=CH-CH_2-Br \xrightarrow{Zn (dust)} (A)$
Above reaction is an example of $1,4$-elimination. Predict the product.