The rigth answer is D.
The wavefront or wavefront is an equal phase surface of a wave, i.e., these points have the same travel time from the source. The concept is used to describe the propagation of waves such as sound or electromagnetic radiation (light, radio waves, etc.). In a homogeneous and isotropic medium, in which the waves propagate without deformation, two types of particular waves are distinguished according to whether the wavefronts are spheres (spherical wave) or planes (plane wave).
Answer:
The correct answer is option a, that is, 3000 cases.
Explanation:
The measurement of all the individuals getting influenced by the disease at a specific time is known as the prevalence. On the other hand, the measurement of the number of novel individuals that came into contact with a disease during a specific time duration is known as the incidence.
Based on the given question, the number of prevailing cases carried from 2018 to 2019 is 2000, and the new diseases recorded in the year 2019 is 1000 (incidence). Therefore, the prevalence of the disease in 2020 will be 3000 cases.
In order to conduct a research you should have an dependent variable, independent variable and the control variable. so in order to study phototropism, then you should need sun light and the growth of the plant and you must have a control that why you need a dark room.
The answer for your question is 1. Easy to grow crops
