Which of the following is an example of situational irony?

a. The cat ran away from the dog.
b. She told everyone what a beautiful day it was.
c. A vampire has a cross in his house.
d. Penny is beautiful.

c. A vampire has a cross in his house.

The correct answer is c. A vampire has a cross in his house. This is an example of situational irony because vampires are traditionally depicted as being repelled by crosses.

To identify an example of situational irony, we need to understand the concept of situational irony first. Situational irony occurs when there is an unexpected outcome or contradiction between what is expected to happen and what actually happens in a particular situation.

Now, let's go through the given options and determine which one is an example of situational irony:

a. The cat ran away from the dog.
This scenario does not involve any unexpected outcome or contradiction. It is a straightforward situation where a cat, which is typically afraid of dogs, ran away from a dog. Therefore, this is not an example of situational irony.

b. She told everyone what a beautiful day it was.
Again, this option does not suggest any unexpected outcome or contradiction. It simply states that someone expressed their opinion about the weather, so there is no situational irony involved here.

c. A vampire has a cross in his house.
This example represents situational irony because it contradicts the common belief that vampires are repelled by religious symbols, such as crosses. Typically, vampires are considered fearful or harmed by the presence of a cross. Therefore, a vampire having a cross in his house is an unexpected situation and qualifies as situational irony.

d. Penny is beautiful.
This option does not involve any unexpected outcome or contradiction either. It straightforwardly states that Penny is beautiful, so it is not an example of situational irony.

In conclusion, the example of situational irony among the given options is:
c. A vampire has a cross in his house.