Question

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Explanation:

Analyze Jordan's hypothesis

Jordan's hypothesis is that the juice is the only part of the lemon that is effective at removing stains because it is an acid. To test this scientifically, he needs to isolate variables and test the specific claims of his hypothesis.

Evaluate testing different parts

Using the Experimental Design knowledge point:
Jordan must test whether other parts of the lemon (pulp, skin) also remove stains. Making identical stains on T-shirts and applying different parts of the lemon directly tests if only the juice is effective.

Evaluate testing the acidity claim

Using the Scientific Variables knowledge point:
Jordan's hypothesis attributes the stain-removing ability specifically to the juice's acidity. To test if acidity is the active variable, he should compare lemon juice with other acidic juices to see if they also remove stains.

Eliminate non-scientific options

Opinion polls and housekeeping website claims do not provide empirical, controlled experimental evidence. Testing the acidity of different parts of the lemon alone does not test their stain-removing effectiveness.

Answer:

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