BOILING POINT $-$ COMPOSITION CURVE

Mol $\%$ A

If a $50/50$ solution of compounds A and $B$ are boiled, what would be the approximate composition of the vapors initially formed? HINT: I am asking for the composition of the vapor before any of the additional condensation and vaporization processes that would take place in a fractioning column.

$($Multiple Choice: Only one answer is correct, and only one answer can be selected$)$

O$\%$A and $100B$

$20\%$A and $80\%B$

$40\%$A and $60\%B$

$60\%$A and $40\%B$

$80\%$A and $20\%$B

$100\%$A and $0\%B$