The figures show diagramatic representations of vector fields $\vec{X}, \vec{Y}, \text{and} \vec{Z}$ respectively. Which one of the following choices is true?
- $\bigtriangledown . \vec{X}=0,\bigtriangledown \times \vec{Y} \neq 0, \bigtriangledown \times \vec{Z}=0$
- $\bigtriangledown . \vec{X} \neq 0,\bigtriangledown \times \vec{Y} = 0, \bigtriangledown \times \vec{Z} \neq 0$
- $\bigtriangledown . \vec{X} \neq 0,\bigtriangledown \times \vec{Y} \neq 0, \bigtriangledown \times \vec{Z} \neq 0$
- $\bigtriangledown . \vec{X}=0,\bigtriangledown \times \vec{Y} = 0, \bigtriangledown \times \vec{Z}=0$