The correct option is
B Conjoint, collateral and closed
A.Conjoint, collateral, open - Dicot stem
B.Conjoint, collateral, closed - monocot stem
C.Conjoint, bicollateral, open - stems of cucurbitaceae.
D.Conjoint, concentric, closed - not found in any plant part.
So, the correct option is 'Conjoint, collateral, and closed'.