Let $\overrightarrow{\mathrm{a}},\overrightarrow{\mathrm{b}}\text{ and }\overrightarrow{\mathrm{c}}$  be three  units vectors such that $3\overrightarrow{\mathrm{a}}+4\overrightarrow{\mathrm{b}}+5\overrightarrow{\mathrm{c}}=0$ Then which of the following statements is true?

• A

  $\overrightarrow{a}\text{ is parallel to }\overrightarrow{b}$

• B

  $\overrightarrow{a}\text{ is perpendicular to }\overrightarrow{b}$

• C

  $\overrightarrow{a}\text{ is neither parallel nor perpendicular to }\overrightarrow{b}$

• D

  none of these