What's the action verb ?

when people discover gold and silver , mining became a major industry

a people
b discovery
c mining
d became

Unit testactivelike sparkling stars strewn across the night sky.their brilliance catching the corner of my eye,making me slow down, just to look at them a little longer.in my awe of the sheer beauty of merely broken glass,i couldn't but thinkhow someone else's tragedycould be so beautiful to me.source: t., jennifer. "irony." teen ink. teen ink, n.d. web. cjuly 2011.the poem is an example ofexternal conflictinternal conflictdramatic ironysituational ironymark this and returnsave and exitsubmit