A．Sleep apnea will necessarily lead to depression.
B．Half of the people suffering sleep apnea will become depressed.
C．The relationship between sleep apnea and depression still needs further proof.
D．There is no connection between sleep apnea and depression.

A．The US government's monthly employment report.
B．The US government's monthly tax report.
C．The US government's monthly budget report.
D．The US government's monthly deficit report.

A．It's entirely the fault of Europe's leaders.
B．It's entirely the fault of the US politicians.
C．It's not entirely the fault of Europe's leaders.
D．It's not entirely the fault of the US politicians.