What sentence from the excerpt contains evidence of douglass’s misery at being denied an education?

a. she at first lacked the depravity indispensable to shutting me up in mental darkness.
b. during this time, i succeeded in learning to read and write.
c. in accomplishing this, i was compelled to resort to various stratagems.
d. it is due, however, to my mistress to say of her, that she did not adopt this course of treatment immediately.