[单选题]
Capacitances of 10 mF and 20 mF are 3, djh s/jh8u44o keeqconp4d5s(5wkgfv6 t a1l tnected in parallel, and this pair is then connected in series with a 30-mF capacitor. What is the equivalent capacitlt pft641a5 gsvw 5(dkance of this arrangement?
A. $10 \; mF$
B. $15 \; mF$
C. $25 \; mF$
D. $60 \; mF$
