*Question*
You are presented with the question "What forms silica sand?" and the following answer choices: - Sediment - loose soil - sunlight - fire - soft soil - erosion - gasoline - rocks Now knowing that erosion causes deposition and silica sand is primarily mined from sandstone deposits, choose the best answer.
**Answer**
erosion

*Question*
You are presented with the question "Which of the following is sometimes used to indirectly heat buildings?" and the following answer choices: - hydrogen and oxygen - carbon monoxide - direct energy - dropping spheres - electromagnetic energy - a hydraulic system - nuclear fission - farm animals Now knowing that electricity sometimes is used for heating buildings and nuclear fission is the only method currently used by nuclear plants to generate electricity, choose the best answer.
**Answer**
nuclear fission

*Question*
You are presented with the question "What is is the average number of individuals per unit of area or volume?" and the following answer choices: - solid, liquid, gas - Earth orbiting the Sun - competing for resources - measure of growth - more abundant - it keeps an organism warm - fur and fat - competition Now knowing that population density is the average number of individuals per unit of area or volume and another measure of growth is population density, choose the best answer.
**Answer**
measure of growth

*Question*
You are presented with the question "What requires investment, seed mass, size and dispersal?" and the following answer choices: - plants - Species - animals - coral - Oak - gene flow - Frogs - mussels Now knowing that plant requires seed dispersal for reproduction and reproductive investment was measured as seed mass, samara size, and dispersal ability, choose the best answer.
**Answer**
plants