You analyze a dna sample and find that its base composition is 30% a, 20% t, 30% g, and 20% c. what can you conclude about the structure of this dna?
because a equals g, and t equals c, this must be a double-stranded dna molecule.
because a does not equal t, and g does not equal c, this cannot be a double-stranded dna molecule. it must therefore be a single-stranded dna.
because a is half as much again as t, and g is half as much again as c, this must be a mutated double-stranded dna molecule.
there is not enough information to determine whether it is a single-stranded or a double-stranded dna molecule.

Because A does not equal T, and G does not equal C, this cannot be a double-stranded DNA molecule. It must therefore be a single-stranded DNA.

Explanation:

The base composition in the observed DNA sample does not follow the Chargaff rule. If it was a double-stranded DNA, the percent proportion of adenine base and thymine base should be equal (either 30% or 20% for both). Similarly, the percent proportion of guanine and cytosine bases must also be equal  (either 30% or 20% for both). Since the given sample does not follow it, it is not a double-stranded DNA molecule but is present as a single strand.

it also supports my hypothesis. if you rest first you can squeeze the clothespin more times. from the data i collected the average of the eight people concluded exercise makes your muscles more fatigued and less able to squeeze the clothespin compared to resting before squeezing.