Jordan's grandmother uses the juice from squeezed lemons to remove stains from his shirt. He hypothesizes that the juice is the only part of the lemon that is effective at removing the stains, because it’s an acid. Which two steps would help Jordan determine whether his hypothesis is scientifically supported?

He should test the acidity of different parts of the lemon, including the juice, pulp, and skin.
He should conduct an opinion poll of residents to see if they agree with his hypothesis.
He should make identical stains on T-shirts and see whether different parts of the lemon will remove the stain.
He should find literature on housekeeping websites that support the use of lemon juice at removing stains.
He should compare lemon juice with other acidic juices to see if they all remove stains.