Universal Container’s Salesforce admin changed some field types from Date to Date/Time. What will happen for the data populated in the fields that are already in Salesforce?

Answer options:

A.Time will be added automatically to the existing fields when the change happens
B.Salesforce doesn’t allow the change of the field type from Date to Date/Time
C.Nothing will happen, data will stay the same without any change
D.Data loss will occur

Correct Answer: D 
Whenever the field type is changed from Date to Date/Time, data loss will occur. 
Option A is incorrect because time cannot be added automatically to the existing fields. It was not there from the beginning since it was a date field, so the system doesn’t have a record about the time. 
Option B is incorrect because Salesforce allows the change of field type from Date to Date/Time 
Option C is incorrect because the data will not stay the same, It will be lost. 
Reference: 

https://help.salesforce.com/articleView?id=notes_on_changing_custom_field_types.htm&type=5