Which of the following PHP extensions allows CRUD functions across multiple type of database?Question 27Select one:a.ORACLEb.MySQLc.PDOd.DSNe.LocalHost

The PHP extension that allows CRUD (Create, Read, Update, Delete) operations across multiple types of databases is PDO (PHP Data Objects). So, the answer is c. PDO.

Here's why:

PDO is a database access layer providing a uniform method of access to multiple databases. It doesn't understand the database-specific SQL, but it allows you to use any database without having to use different function calls for the different databases.

Other options like Oracle, MySQL are specific to their respective databases. DSN (Data Source Name) is not a PHP extension but a string that has the information you need to connect to the database. LocalHost is a hostname that means 'this computer,' and it is used to access the network services that are running on the host via the loopback network interface.

So, PDO is the correct answer because it provides a consistent interface for accessing several types of databases and allows developers to use multiple types of databases in the same application with ease.