The answer would be absorbed
I am not sure about .030 but i would pick c
.025) b
26)c
27)d
28)d
1st and 4th options are suitable answers, as these 2 changes are not exactly physical changes as it cant return back to original form and as well as its not cooling, so I feel its 1st and 4th options
He is missing a (real) control. Growing two plants without plant food at all doesn't count; in order to see if the new food is better, he must also grow plants with the original food in order to compare it.
He does have an independent variable. This is the type of plant food. It's independent because he has direct control over it.
He needs to give plants the same conditions besides food: same water (amount), same light exposure, same temperature, etc.
He needs to choose a quantitative way to measure how much the plants grew, like mass or length.
