A project manager needs to purchase parts for a project. Two suppliers are found and both of them have been used before and have delivered on time 90% of the time and have been late 10% of the time. If the project manager splits the order between the two suppliers, what is the probability that at least one of them will deliver the parts on time?
a. 81%
b. 180%
c. 99%
d. 100%
99%