The consecutive angles of a trapezoid form an arithmetic sequence. If the smallest angle is $75^\circ$, then the largest angle is
$\text{(A) } 95^\circ\quad \text{(B) } 100^\circ\quad \text{(C) } 105^\circ\quad \text{(D) } 110^\circ\quad \text{(E) } 115^\circ$
A trapezoid is a quadrilateral; therefore the interior angles sum to $360^\circ$.
Thus $75+(75+x)+(75+2x)+(75+3x)=360$, so $x=10$ and the largest angle is $105^\circ$ which is $\fbox{C}$