[单选题]
Capacitances of 10 mF a1c.g*fwq 1 nfrnd 20 mF are .cszos:u i5n;6uqxv- connected in parallel, and this pair is then c65nx.sz :vcq;o- uui sonnected in series with a 30-mF capacitor. What is the equivalent capacitance of this arrangement?
A. $10 \; mF$
B. $15 \; mF$
C. $25 \; mF$
D. $60 \; mF$
