A two-year-old child with a red birthmark that blanches under pressure and darkens when crying is likely to have what prognosis?

The child described in the scenario has a red birthmark that blanches under pressure and darkens when crying, which is characteristic of a capillary malformation, commonly known as a strawberry nevus or infantile hemangioma. These types of birthmarks are generally benign and are known for their typical course of growth and regression.

In many cases, infantile hemangiomas undergo a period of rapid growth in infancy followed by a phase of involution, where they gradually shrink and fade away. By the age of 5 years, a significant number of these hemangiomas will either completely regress or become much less noticeable. This benign nature and the likelihood of regression by age 5 makes option C the most appropriate prognosis for the child.

This contrasts with other options like the potential for malignancy or requiring immediate biopsy, which are not consistent with the characteristics of the described birthmark. Malignant conditions typically exhibit different clinical presentations and require distinct management approaches. Thus, the benign nature and the expected regression of this type of birthmark highlight why the prognosis is aligned with the option suggesting it will likely regress by age 5.