The following table shows $\left(x, \; y\right)$ values for a linear function. What is the slope of this function?

A. $6$

B. $2$

C. $12$

D. $7$

E. $1$

$x$ | $y$ |

2 | 15 |

5 | 33 |

9 | 57 |

11 | 69 |

A. $6$

B. $2$

C. $12$

D. $7$

E. $1$