Phát biểu nào sau đây là đúng? A. −−→ A B + −−→ B C = 2 −−→ A C ∀ A , B , C . B. −−→ A B + 2 −−→ B C = −−→ A C ∀ A , B , C .

\(\overrightarrow {{\rm{AB}}} + \overrightarrow {{\rm{BC}}} = 2\overrightarrow {{\rm{AC}}} \forall {\rm{A}},{\rm{B}},{\rm{C}}.\)

\(\overrightarrow {{\rm{AB}}} + 2\overrightarrow {{\rm{BC}}} = \overrightarrow {{\rm{AC}}} \forall {\rm{A}},{\rm{B}},{\rm{C}}.\)

\(2\overrightarrow {{\rm{AB}}} + \overrightarrow {{\rm{BC}}} = \overrightarrow {{\rm{AC}}} \forall {\rm{A}},{\rm{B}},{\rm{C}}.\)

\(\overrightarrow {{\rm{AB}}} + \overrightarrow {{\rm{BC}}} = \overrightarrow {{\rm{AC}}} \forall {\rm{A}},{\rm{B}},{\rm{C}}.\)