Answer:

Introduction:
The Einstein Telescope is an advanced gravitational-wave observatory that is currently in the planning stage. It aims to detect gravitational waves, which are ripples in the fabric of space-time caused by the acceleration of massive objects. These waves provide valuable information about the nature of the universe and can help us study phenomena such as black holes and the early moments of the universe.

Statement 1: It is an advanced gravitational-wave observatory, currently in the planning stage.
This statement is correct. The Einstein Telescope is indeed an advanced gravitational-wave observatory that is currently in the planning stage. It is being developed as a next-generation detector, designed to improve upon the capabilities of existing gravitational-wave observatories such as LIGO (Laser Interferometer Gravitational-Wave Observatory) and Virgo.

The Einstein Telescope aims to surpass the sensitivity of these existing detectors by using new technologies and techniques. It is being designed to detect gravitational waves from various sources, including binary black hole and neutron star mergers, supernovae, and the early moments of the universe. The planning stage involves designing the detector and its infrastructure, as well as securing funding and international collaboration.

Statement 2: Its low-frequency sensitivity will allow us to detect intermediate-mass black holes.
This statement is also correct. The low-frequency sensitivity of the Einstein Telescope will indeed allow us to detect and study intermediate-mass black holes. Intermediate-mass black holes are a class of black holes with masses ranging from a few hundred to several thousand times that of the Sun. They are believed to form through various mechanisms, such as the direct collapse of massive gas clouds or the merging of smaller black holes.

Detecting and studying intermediate-mass black holes is important for understanding the formation and evolution of black holes, as well as their role in the growth of galaxies. The low-frequency sensitivity of the Einstein Telescope will enable it to detect the gravitational waves produced by the mergers of these intermediate-mass black holes, providing valuable insights into their properties and distribution in the universe.

Conclusion:
In conclusion, both statements regarding the Einstein Telescope are correct. It is an advanced gravitational-wave observatory currently in the planning stage, and its low-frequency sensitivity will allow us to detect intermediate-mass black holes. The development of the Einstein Telescope holds great promise for advancing our understanding of the universe and the phenomena within it.