The magnetic flux linked with a coil is $\phi = (3t^2 - 2t + 1)$milli weber. The e.m.f induced in the coil at t = 1 sec is:
(a) $4V$
(b) $4 \times 10^{-3} V$
(c) $6V$
(d) $4 \times 10^3 V$