The log in which data changes received from a replication master server are written is . . . . . . . .

This question asks about where MySQL stores the changes made to data on a server. Let's break down the options:
Option A: error log - This log records errors that occur during the operation of the MySQL server. It doesn't store data changes.
Option B: general query log - This log keeps track of all the SQL queries that are executed on the server. It doesn't specifically store changes to data.
Option C: binary log - This log records all changes made to the data on the server, including updates, inserts, and deletes. It's used for replication, where changes are copied to other servers.
Option D: relay log - This log is used by slave servers in a replication setup. It stores the changes received from the master server and applies them to the slave server's database.
Therefore, the correct answer is Option D: relay log.
Let's summarize:
* Binary log: Stores changes from the master server.
* Relay log: Stores changes received from the master server and applies them to the slave server's database.