If the variable cost per unit goes down, which impact is correct?If the variable cost per unit goes down, which impact is correct?

$\backslash$table$[[,$Contribution Margin,Break$-$even point$],[$a$,$increases,increases$],[$b$,$increases,decreases$],[$c$,$decreases,decreases$],[$d$,$decreases,increases$],[$e$,$decreases,remains unchanged$]]$