Correct

膀子

/ bǎngzi / 
Strokes

Definition

upper arm/arm/wing

Example

As a Noun

upper arm; arm

1
Guāng
光
zhāo
着
bǎngzi
膀子

with one's upper part naked; bare down to the waist

As a Noun

wing

2
Lǎoyīng
老鹰
shòushāng
受伤
de
的
bǎngzi
膀子

the injured wing of the eagle