What is the integrating factor for

$1+$sec$2=3421$ydydx$+$sec$2$x$=3$x$42$y$?$

Select one:

a$.$

$$tan$$etanx

b$.$

$3424$e$34$x$24$x

c$.$

$$sec$$tan$$esecxtanx

d$.$

$66+842$