You need to process over 50,000 Contact records and run it once daily after business hours, so your solution must support:
Large data volumes → requires Batch Apex
Scheduled execution → requires Scheduled Apex

✅ D. Database.Batchable
Allows you to process millions of records in manageable chunks (default 200 per batch).
Perfect for aggregation, updates, or any heavy processing.

✅ C. Schedulable
Allows you to schedule a class to run at a specific time (e.g., after business hours daily).
You schedule the batch job using System.schedule(...)

❌ B. @future annotation
Has a limit of 50 records per method call
Not designed for large data processing
Cannot be scheduled directly

❌ A. Queueable interface
Better than @future but still not suited for massive record volumes
Not ideal when working with more than 50,000 records

can you please correct the answer . it should be schedulable with batch Apex. not future method

Option C is correct because implementing the Schedulable interface allows you to schedule the class to run at specified times, such as after business hours, which is a requirement for this scenario.
Option D is correct because the Database.Batchable interface is what's needed for processing large datasets like morethan 50K records.