One Day, a Classmate with Whom You've Been Trying to Go

Multiple Choice

One day, a classmate with whom you've been trying to go out socially gives you her phone number, which you write on your hand. However, as you try to put the number into your phone later, you cannot make out the last number. If you punch in the area code and the first six numbers plus "0", then punch in the first six digits plus "1", then the first six digits plus "2", etc. until you get the correct number, you are solving your problem by

A) using heuristics.
B) rote.
C) trial and error.
D) insight.