$\backslash$table$[[$DC$,$Customer$],[$A$,$B$,$C$,$Supply$],[2,4,6,8,500],[3,5,2,7,400],[$Demand$,3,5,9,300],[,200,350,400,]]$

The constraint that represents the quantity demanded by Customer $B$ is:

A$)6x_{1B}+2x_{2}B+8x_{3B}350$

B$)6x_{1}B+2x_{2}B+8x_{3}B=350$

C$)x_{1}B+x_{2}B+x_{3B}350$

D$)x_{1}B+x_{2}B+x_{3}B=350$