Which of these graphs do not represent constant rates of change?

Atemperature of 1.64◦f corresponds to answer in units of ◦c.

Avery’s piggy bank has 300 nickels, 450 pennies, and 150 dimes. she randomly picks three coins. each time she picks a coin, she makes a note of it and puts it back into the piggy bank before picking the next coin.

Ithink i know it but i want to be sure so can you me out ?