Every Saturday, Justin gets an allowance of $10 from his parents. During every week since Justin began getting an allowance, he spends $8 and saves the remaining $2 of his allowance before he receives his next allowance. The sequence shown represents the amount of money Justin has right before and right after he gets his allowance for six consecutive weeks, starting with $0. 0, 10, 2, 12, 4, 14, 6, 16, 8, 18, 10, 20

Explain why this sequence is or is not a function?

A.

This sequence is not a function because the amount $10 appears in the sequence more than once.

B.

This sequence is not a function because the sequence does not form a line.

C.

This sequence is a function because each input (odd terms in sequence) maps to one output (even terms in sequence).

D.

This sequence is a function because each output (even terms in sequence) maps to one input (odd terms in sequence).
Thanks! I'm stuck between C, D and A