What is the explicit formula for this sequence?

Question

5, 10, 20, 40, 80, 160

A. a_n = 5(2)^(n-1)

B. a_n = 2(5)^(n-1)

C. a_n = 5 + 5(n-1)

D. a_n = 5(2)ⁿ

^{*im stuck between b and d for the answer}

Answer 1

A geometric sequence is defined by

a_n = a₁(r)^n-1

Answer 2

Which one does this look like according to PEDMAS as in do evaluate the exponent first to remove the parentheses.

5(2)⁰ = 5*1 = 5

5(2)¹ = 5*2 = 10

5(2)² = 5*4 = 20

5(2)³ = 5*8 = 40

5(2)⁴ = 5*16 = 80

5(2)⁵ = 5*32 = 160

Does B satisfy all the values?

I am rather stuck on D

I hope you find this useful.