This question is incomplete, the complete question is on the image uploaded along this answer.
Answer:
the potential at point B is 5 V, Option d) is the correct answer
Explanation:
Given that;
from the image;
R = 3 + 4 + 5 = 12 Ω
so I = 12/12 = 1 A
Q = 0 + 12 = 12 V
now
VA - VQ = - I × 3 = -3 V
VA = VQ - 3 = 12 - 3 = 9 V
VB - VA = - I × 4Ω = - 4 V
⇒VB = VA - 4 = 9 V - 4 V = 5 V
Therefore the potential at point B is 5 V
Option d) is the correct answer
