'Plumb' refers to:
Ahorizontal alignment
Bperfect verticalityCORRECT
Cdiagonal alignment
Dweight measurement
NABTEBBlock-laying & Concreting
AI
Toaster Teacher
Why the answer is B, and why the others tempt you.
A plumb wall is perfectly vertical, checked using a plumb line/level.
Want this in Pidgin, Yoruba, Igbo or Hausa? Sign up free →
Practice more Block-laying & Concreting questions
NABTEB Block-laying & Concreting has thousands more questions like this — with Worked answers on every one.