Which of the following is the equation of a circle whose center is at the origin and whose radius is 4? x^2+y^2=2 x^2+y^2=4 x^2+y^2=16

Masons cell phone company charges $0.12 for every text message he sends plus $2.50 per month if mason sent 25 messages this month how much money does he owe the one with the correct answer and explanation gets 10 points and is marked as the brainliest answer