Choose the One Alternative That Best Completes the Statement or Answers

Multiple Choice

Choose the one alternative that best completes the statement or answers the question.
- $$a _ { 1 } = z ; a _ { n } = a _ { n - 1 } + U$$

A) $U , U + z , U + 2 z , U + 3 z$
B) $z , z + U , z + 2 U , z + 3 U$
C) $z , U , 2 U , 3 U$
D) $z , z - U , z - 2 U , z - 3 U$