下列分子式表示的物质一定是纯净物的是 [ ]

A．C₅H₁₀

B．C₇H₈

C．CH₄O

D．C₂H₄Cl₂

What's the most appropriate nursing diagnosis for a client exhibiting obsessive-compulsive behavior

A．Ineffective coping.

B．Imbalanced nutrition: Less than body requirements.

C．Imbalaneed nutrition: More than body requirements.

D．Interrupted family processes.