[单选题]
An object is 15 mm in front of a coeg c wpy8s.3-5adk ir3 l)u4p6tv qj8rnverging lens, and:+9yjkxu,r zk4 b(j g7 c4nlhx 9w;mfd the image is 4.0 mm behind the lens. What is the focal (h7d g xr,f+jj9;4:myn 9 cwlkbx4zk ulength of the lens?
A. $11 \; mm$
B. $5.5 \; mm$
C. $3.8 \; mm$
D. $3.2 \; mm$
