Problem: Alexandra and Tomas enter into a contract in which Tomas agrees to install a new door for Alexandra and to install a new silver doorknob. Tomas installs the door, but silver doorknobs are out of stock so he finds a chrome knob that he believes looks silver and he installs it. Which of the following describes Tomas' performance of his duties? Multiple Choice Complete performance Substantial performance Commercial impracticability Frustration of purpose Promissory estoppel