CEMC Fermat, 2008

Algebra Difficulty 2.0 Junior Find the answer Canada

An $\emph{arithmetic}$ sequence} is a sequence in which each term after the first is obtained by adding a constant to the previous term. If the first four terms of an arithmetic sequence are $a$ , $2a$ , $b$ , and $a-6-b$ for some numbers $a$ and $b$ , then the value of the $100$ th term is

(A) $-100$ (B) $-300$ (C) $150$ (D) $-150$ (E) $100$

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