Carl has already earned $60 mowing lawns. He earns $15 per lawn. He needs at least $115 for a new string trimmer. Write and solve an inequality to determine how many more lawns Carl will need to mow to have at least $115.
A. at least 3 lawns
B. no more than 4 lawns
C. at least 4 lawns
D. at least 5 lawns