Correct

不力

/ bùlì /
Strokes

Definition

not to do one's best/not to exert oneself

Example

As an Adjective

ineffective; incompetent

1
Duì
fànzuìfèn
犯罪分子
打击
不力

fail to launch an effective crackdown against criminals

2
Lǐngdǎo
领导
不力

have slack/weak leadership; not exercise effective leadership

3
Bànshì
办事
不力

not exert oneself with one's work; be slack in one's work; lack efficiency/capability with one's work