The correct option is
A 8
The length of BD is equal to the sum of the other two sides.
The steps of construction of a triangle when its base, a base angle and sum of other two sides are given are :-
1. Draw base BC = 5 cm and construct ∠ B= 60.
2. With centre B and radius 8cm (AB + AC = 8 cm) draw an arc to cut BX at D.
3. Join CD and draw the perpendicular bisector of CD to meet BD at A.
4. Join AC to get the required triangle ABC.
Hence, the length of BD is found to be 8 cm.