The formula for any arithmetic sequence is an = a1 + d ( n - 1), where an represents the value of the n th term, a1 represents the value of the first term, d represents the common difference, and n represents the term number. What is the formula for the sequence 10, 8, 6, 4, ...?

an = 10 + (-2)( n - 1)
an = 10 + 2( n - 1)
an = -2 + 10( n - 1)
an = 2 + 10( n - 1)