A hydrocarbon of formula ${\mathrm{C}}_6{\mathrm{H}}_8$ absorbs two mole of ${\mathrm{H}}_2$ upon hydrogenation. On ozonolysis, it yields Propanedial. What is hydrocarbon?

Alkynes $\left(\mathrm{A}\right)$ and $\left(\mathrm{B}\right)$ have the molecular formula ${\mathrm{C}}_8{\mathrm{H}}_{14}$ giving following reactions :

$\left(\mathrm{A}\right)$ or $\left(\mathrm{B}\right)\stackrel{{\mathrm{H}}_2/\mathrm{Pt}}{⟶}$ n-Octane.

$\left(\mathrm{A}\right)\stackrel{{\mathrm{O}}_3/{\mathrm{H}}_2\mathrm{O}}{\to }$${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{CO}}_2\mathrm{H}$

$\left(\mathrm{B}\right)\stackrel{\left[\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_2\right]\mathrm{OH}}{\to }$white ppt. containing silver

Write the structure of $\left(\mathrm{A}\right)$ and $\left(\mathrm{B}\right)$.