$\overrightarrow{\mathrm{a}}=\widehat{\mathrm{i}}+2\widehat{\mathrm{j}}+3\widehat{\mathrm{k}},\overrightarrow{\mathrm{b}}=2\widehat{\mathrm{i}}-\widehat{\mathrm{j}}+\widehat{\mathrm{k}}\text{ and }\overrightarrow{\mathrm{c}}=3\widehat{\mathrm{i}}+\widehat{\mathrm{j}}+4\widehat{\mathrm{k}}$  vectors are so placed that the end point of one vector is the starting point of the next vector. Then the vectors are

• A

  not coplanar

• B

  coplanar but cannot form a triangle

• C

  coplanar and form a triangle

• D

  coplanar and can form a right-angled triangle