Fred is conducting a controlled experiment to test whether using a grow light at night will help a tomato plant grow faster. Below are the steps to Fred's experiment: Plant tomato plants in two separate, but identical, flowerpots. Place the flowerpots in the same area outside during the day. At night, bring both flower pots inside and place one in the dark and one under a grow light. Give the plants the same amount of food and water each week. Measure the growth of the plants. Draw conclusions based on the data collected. Which of the following variables must Fred hold constant in this experiment? A. the type of tomato plants used B. the amount of time both plants spend in the dark C. the length of time this experiment is carried out D. the amount of time both plants spend in the light

What is the relationship between wind and ocean waves? question 17 options: wind moving at higher speeds will transfer more energy to the water, resulting in stronger waves. wind moving at higher speeds will transfer energy over a larger part of the ocean water, resulting in waves with a shorter wavelength. winds moving at higher speeds with cause water to move forward at faster rates, causing larger ocean waves. winds moving at higher speeds will affect deeper water, resulting in waves that move at a faster rate. how do temperature and salinity affect deepwater currents? question 15 options: as temperatures and salinity levels of water increase, the water rises to the surface where it creates currents as it moves to colder regions. they create changes in wind direction, moving denser water in the same direction as the wind and causing the deepwater circulation patterns found in the ocean. they equalize the forces on undersea currents caused by the coriolis effect as they replace more dense water with less dense water. they create density differences that cause dense deepwater currents to flow toward the equator where they displace less dense, warmer water above them.