D.A man plans a July picnic in the Mojave Desert, but it is spoiled by rain.
Irony is when the opposite of what is expected happens. The man planned the picnic in July in the Mojave Desert because it is unlikely to rain in the desert, especially at this time. The situation is ironic because it does rain! This is the opposite of what is expected. The other options do not have situations that are the opposite of what is expected. The shy person is too nervous to give a speech, but nothing else is stated. Boston schools cancel school because of a snowstorm in the winter. A popular band sells out each performance. These are all expected circumstances.
