Mosses grow close to the ground because they
a. lack the nutrients needed to grow tall.
b. lack vascular tissue.
c. need direct sunlight.
d. do not perform photosynthesis.

The best answer is B.

Mosses grow close to the ground because they have no vascular tissue or system. A vascular system in plants can simply be described as a series of tubes that can transport water and nutrients over a distance from one part of the plant to another. Because of this, mosses unlike other plants such as trees  must be close to the water source on the ground to be able to take up water and nutrients.

Trees have a vascular system which enables them to transport water and nutrients over a large distance and can thus afford to grow tall sometimes over 100 ft  tall like the redwood and sequoia trees.

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.