A solar eclipse is caused when the-
A. Sun comes in between the earth and the moon
B. Moon comes in between the sun and the earth
C. Earth comes in between the sun and the moon
D. None of these

Hint: Since, we are asked about a natural phenomenon, we could simply recall how the process actually happens. You could think like this, since the name suggests that the sun is getting eclipsed we could think of the cause that would result in that. Thus, you will get the answer.

Complete answer:
In the question, we are asked to find the correct one among the given options that gives a condition when a solar eclipse is said to occur.
A solar eclipse is known to occur when a portion of the Earth gets into the shadow that is being cast by the moon which further blocks the sunlight fully or partially. Also, the Sun, the moon and the Earth should be aligned for the solar eclipse to occur. Normally for a total eclipse, the Sun’s disc is obscured by the moon while it is obscured partially for partial or annular eclipses.
The total eclipses are normally considered rare because this requires the timing of the new moon to coincide with the eclipse season.
Therefore, we found that the moon comes in between the sun and the earth and thereby the shadow of the moon falls on earth as the sun gets eclipsed. Hence, option B is correct.

Note:
Though the solar eclipse is a natural phenomenon, it stood for supernatural causes and also bad omens in ancient and modern cultures. What we see in real life is the sun disappearing during the day and the sky darkening in those minutes. Also, looking at this event with a naked eye causes permanent eye damage and hence an eye protection is advised.