A student is investigating gas production of water plants of various sizes. She predicts that larger plants produce more oxygen. She places a test tube and funnel upside down over a water plant submerged in water. The test tube collects gas the plant produces when in sunlight. A diagram of her setup is shown below. In this experiment, what is the independent variable?
A. The number of gas bubbles
B. The varying size of the plants
C. The test tube used to collect gas
D. The temperature of water in the beaker

The test tube used to collect gas (C)

Explanation:  If you illuminate a plant (I presume you are using an aquatic/water plant) it will produce oxygen. You can put the plant under a funnel and collect the bubbles in an upturned test tube. If the gas is collected fresh, it will relight a glowing splint. However, if the gas takes more than 24 hours to collect, or if you leave it for several hours before testing it, you may not relight a glowing splint.

not the best question format lol but what i think might as scale color is controlled by a single gene with two alleles, the green allele and the yellow allele. when moths that are homozygous for green scales are mated with moths that are homozygous for yellow scales, 100% of the offspring have green scales.