Final answer:
The most likely etiology of the birth defects described is Trisomy 13 (Patau syndrome), which is option C. It is a condition associated with characteristic defects such as cleft lip, extra digits, and small eyes, unlike Trisomy 21 or specific chromosomal deletions.
Step-by-step explanation:
The child born with several birth defects such as a cleft lip, extra digits, and extremely small eyes is most likely affected by Trisomy 13, which is option C. Trisomy 13, also known as Patau syndrome, is caused by having three copies of chromosome 13 and often results in a variety of congenital anomalies. Some of the features of Trisomy 13 include cleft lip or palate, polydactyly (extra digits), and microphthalmia (abnormally small eyes). It is not associated with the age of the birth parent as with Trisomy 21, which is more common with advanced maternal age.
Trisomy 21, or Down syndrome, is characterized by intellectual disability, vision problems, and a specific facial appearance, but does not typically present with the aforementioned defects. This condition increases in incidence with the maternal age, particularly for mothers over 35. While chromosomal deletions like deletions of 11p13 or 5p can lead to genetic disorders (such as WAGR syndrome or Cri-du-chat syndrome, respectively), they do not typically present with the cluster of symptoms described in the question.