Two cars of masses $m_1$ and $m_2$ are moving in circles of radii $r_1$ and $r_2$, respectively. Their speeds are such that they make complete circles in the same times t. The ratio of their centripetal acceleration is
( A ) $1 : 1$
( B ) $m_1r_1 : m_2r_2$
( C ) $r_1 : r_2$
( D ) $m_1 : m_2$