The questions choices are not correct or typo
A. No data is lost when changing Picklist to Multipicklist - True
B. Data can be lost when changing from Rich Text to Long Text - True
C. Data is lost when changing Number to Currency - True
D. Rollup summary fields will stop calculate if Master Detail is changed to lookup - False
E. No data is lost when converting Text to auto number - True
So answers are A, B, C, E ????

https://help.salesforce.com/s/articleView?id=sf.notes_on_changing_custom_field_types.htm&type=5
Only convert custom fields that there’s no data for or you risk losing your data. Changing the data type of an existing custom field can cause data loss in these situations:
Changing to Number from any other type
Changing to Currency from any other type --> C. Data is lost when changing Number to Currency - True
Changing from Picklist (Multi-Select) to any other type
Changing to Picklist (Multi-Select) from any other type
Currently defined picklist values are retained when you change a picklist to a multi-select picklist. If records contain values that aren’t in the picklist definition, those values are deleted from those records when the data type changes.
Changing from Auto Number to any other type
Changing to Auto Number from any type except Text --> E. No data is lost when converting Text to auto number - True
Changing from Text Area (Long) to any type except Email, Phone, Text, Text Area, or URL...