If vectors $|a⃗|=3$ and $|b⃗|=7$, and $a⃗\cdot b⃗=14.85$, determine the angle between vectors $a ⃗$ and $b ⃗$.

• A. $21\degree$
• B. $1.0\degree$
• C. $45\degree$
• D. $14.85\degree$