A cell phone provider charges $69.99 per month for unlimited phone calls plus 5 cents per text message. Which of these is the correct number sentence to describe the cost of the cell phone usage for 6 months and 350 text messages each of those months?

a
$69.99 + ($0.05 x 350 x 6) = $174.99

b
($69.99 + 6) + (350 x $0.05) = $93.49

c
($69.99 x 6) + (350 x $0.05 x 6) = $524.94
d
($69.99 + $0.05) x 6 + 350 = $770.24