MyBatis Database Environment Configuration with Pooled Data Source

In a MyBatis configuration file, the '' element is used to configure the database environment, including the configuration of the transaction manager and data source. Which of the following code snippets correctly configures the database environment and configures a pooled data source?

OA

<environments default="development">
  <environment id="development">
    <transactionManager type="JDBC"/>
    <dataSource type="UNPOOLED">
      <property name="driver" value="$jdbc.driver"/>
      <property name="url" value="$jdbc.url"/>
      <property name="username" value="$jdbc.username"/>
      <property name="password" value="$jdbc.password"/>
      <property name="poolMaximumActiveConnections" value="$jdbc.maxPoolSize"/>
      <property name="poolMaximumIdleConnections" value="$jdbc.maxIdle"/>
      <property name="poolTimeToWait" value="$jdbc.maxWait"/>
    </dataSource>
  </environment>
</environments>

OB

<environments default="development">
  <environment id="development">
    <transactionManager type="JDBC"/>
    <dataSource type="UNPOOLED">
      <property name="driverClassName" value="$jdbc.driver"/>
      <property name="url" value="$jdbc.url"/>
      <property name="username" value="$jdbc.username"/>
      <property name="password" value="$jdbc.password"/>
      <property name="poolMaximumActiveConnections" value="$jdbc.maxPoolSize"/>
      <property name="poolMaximumIdleConnections" value="$jdbc.maxIdle"/>
      <property name="poolTimeToWait" value="$jdbc.maxWait"/>
    </dataSource>
  </environment>
</environments>

OC

<environments default="development">
  <environment id="development">
    <transactionManager type="JDBC"/>
    <dataSource type="POOLED">
      <property name="driverClassName" value="$jdbc.driver"/>
      <property name="url" value="$jdbc.url"/>
      <property name="username" value="$jdbc.username"/>
      <property name="password" value="$jdbc.password"/>
      <property name="poolMaximumActiveConnections" value="$jdbc.maxPoolSize"/>
      <property name="poolMaximumIdleConnections" value="$jdbc.maxIdle"/>
      <property name="poolTimeToWait" value="$jdbc.maxWait"/>
    </dataSource>
  </environment>
</environments>

OD

<environments default="development">
  <environment id="development">
    <transactionManager type="JDBC"/>
    <dataSource type="POOLED">
      <property name="driver" value="$jdbc.driver"/>
      <property name="url" value="$jdbc.url"/>
      <property name="username" value="$jdbc.username"/>
      <property name="password" value="$jdbc.password"/>
      <property name="poolMaximumActiveConnections" value="$jdbc.maxPoolSize"/>
      <property name="poolMaximumIdleConnections" value="$jdbc.maxIdle"/>
      <property name="poolTimeToWait" value="$jdbc.maxWait"/>
    </dataSource>
  </environment>
</environments>

Answer: OC is the correct code snippet as it uses a pooled data source and provides the correct property names for driver class, URL, username, password, maximum active connections, maximum idle connections, and time to wait. It also configures a JDBC transaction manager. The other code snippets either use an unpooled data source or have incorrect property names/values.