Answer:
A) has developed a social allergy
Step-by-step explanation:
Social allergy is the annoyance that is caused by the repeated action or behavior of a person. The behavior seems harmless at first but slowly but surely tends to build up the annoyance of others. The repeated action causes the buildup.
Here, Erica annoyance of David's knuckle cracking over the time they have spent together and she kept it bottled up. But one day she snapped and let it all out.
Hence, Erica has developed a social allergy.