What is the principal part of the underlined verb in the sentence?

have you heard about my trip to the science museum?

a.
past

b.
present

c.
present participle

d.
past participle
i neeed

One person's trash is another person's treasure. instead of discarding unwanted appliances, tools, or clothes, try selling or donating them. karen wants to explain that discarding means "throwing away." which of the following passages has karen written correctly? "one person's trash is another person's treasure. instead of discarding . . throwing away . . unwanted appliances, tools, or clothes, try selling or donating them." "one person's trash is another person's treasure. instead of discarding--throwing away--unwanted appliances, tools, or clothes, try selling or donating them." "one person's trash is another person's treasure. instead of discarding [throwing away] unwanted appliances, tools, or clothes, try selling or donating them." "one person's trash is another person's treasure. instead of discarding (throwing away) unwanted appliances, tools, or clothes, try selling or donating them."