Star clusters are groups of stars which are gravitation-ally bound. Two distinct types of star cluster can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars, while open clusters generally contain less than a few hundred members, and are often very young.
Binary system: a system in which information can be expressed by combinations of the digits 0 and 1. to represent codes and data. Since zeros and ones can be easily represented by two voltages, the binary system is the foundation on which digital technology is built. Every digital computer whether a pocket calculator or a mainframe uses the same binary notation.
The answer to your question is D).
The correct answer is - a convergent boundary, where at least one of the plates is oceanic.
Volcanoes can be formed in multiple types of interactions between the tectonic plates, but most often, they form where there's a convergent boundary between a continental and oceanic tectonic plate. This can easily be seen by the famous ''Ring of Fire'', which is on and around the borders of the Pacific Ocean, and that is due to the heavier Pacific plate subducting beneath the lighter continental plates around it, thus creating a very long chain of volcanoes.
The Sun's rays hit the Earth's surface nearly at right angles at the Earth's equator.
During equinox periods in March and September, the Sun's rays hit the Equator at a perpendicular angle because the Sun is in a position in the sky directly over the Earth's equator. This in turn means that the Sun's rays hit the Earth’s surface nearly at right angles
