Correct

事关重大

/ shìguān zhòngdà /
Strokes

Example

Definition

it's most important; the matter is of great/vital importance

1
Zhè
jiàn
shì
shìguānzhòng
事关重大
  
,
必须
xiǎoxīn
小心
diǎn
  

This is of great importance. You have to be careful.