Question: What is the date of birth of Vichitra Chiraprabha's mother?
Sentence (from "Savang Vadhana"): After her first grandson's accession to power in 1935, she became known as Somdetch Phra Phan Vassa Ayika Chao (สมเด็จพระพันวัสสาอัยยิกาเจ้า; ; "the Queen Grandmother").
Relevant evidence: No