With respect to Visa Numbers for Adjustment Purposes, to which Country Would I be Charged – Birth or Citizenship?

The United States Department of State Foreign Affairs Manual, Volume 9 states,

9 FAM 42.12 N2.1 General Rule of Chargeability

The numerical limitations prescribed in INA 201, 202, and 203 apply to the foreign states and dependent areas. (See 9 FAM 42.12 Exhibits I and II.) An immigrant visa applicant subject to these numerical limitations is generally chargeable to the numerical limitation applicable to the applicant’s place of birth. An immigrant visa applicant born in a dependent area is chargeable to the dependent area (to ensure compliance with the dependent-area limitation imposed in INA 202), as well as to the mother country.

Therefore, in your case, your Visa Number allocation will be based on your Country of Birth – India.