L-isomer of tetrose X ( C_4 H_8 O_4) gives positive Schiff's test and has two chiral carbons. On acetylation, 'X' yields triacetate. 'X' also…

L-isomer of tetrose $\displaystyle \mathrm{X}\left(\mathrm{C}_4 \mathrm{H}_8 \mathrm{O}_4\right)$ gives positive Schiff's test and has two chiral carbons. On acetylation, 'X' yields triacetate. 'X' also undergoes following reactions'A' $\displaystyle \xleftarrow{\mathrm{HNO}_3}$ 'X' $\displaystyle \xrightarrow{\mathrm{NaBH}_4}$ 'B' (Chiral compound)' X ' is