Q. The terms ‘Event Horizon’, ‘Singularity’, ‘String Theory’ and ‘Standard Model’ are sometimes seen in the news in the context of

Answer: (a) Observation and understanding of the Universe

The standard model of particle physics is a mathematical model that describes electromagnetism, the strong and weak nuclear forces, and the Higgs mechanism.
String theory is used in the context of quantum physics that is used to understand quantum phenomena.
The basic structure of a black hole consists of a singularity hidden by an event horizon.
Within the event horizon, the escape velocity exceeds the velocity of the light and an object is trapped forever.

String Theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings.
String theory describes how these strings propagate through space and interact with each other.
On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string.
In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries the gravitational force. Thus, string theory is a theory of quantum gravity.