An unknown compound A has been prepared from the reaction of dehalogenation of a tetra halo derivative with zinc and  B is its positional isomer.  B gives a white precipitate with ammoniacal Silver nitrate but not A. A and B maybe 

• A

  ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{C}\equiv {\text{CH (A) and CH}}_{\text{3}}\text{C}\equiv {\text{CCH}}_{\text{3}}\text{ (B)}$

• B

  ${\text{CH}}_{\text{3}}\text{C}\equiv {\text{CCH}}_{\text{3}}{\text{ (A) and CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{C}\equiv \text{CH (B)}$

• C

  ${\text{CH}}_{\text{3}}\text{CH}=\text{C}={\text{CH}}_{\text{2}}{\text{ (A) and CH}}_{\text{3}}\text{C}\equiv {\text{CCH}}_{\text{3}}\text{ (B)}$

• D

  ${\text{CH}}_{\text{3}}\text{CH}=\text{C}={\text{CH}}_{\text{2}}{\text{ (A) and CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{C}\equiv \text{CH (B)}$