When the switch is open then no current can flow, on the other hand, when it is closed, current will pass through. When only “bulb a” is connected to the battery then more current is flowing to “bulb a” causing it to be bright. So the light of “bulb a” will be dimmer.
Answer:d. Ground waves
Explanation:A P-wave is one of the two main types of seismic waves. P-waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any affected location or at a seismograph
Answer:
• A prism is a polygon and hedron like substance [ polyhedron ] with polygonal edges hence forming rectangular, rhombical or pallarelogramic surfaces.
• There are four prism types;
- Reflecting prisms
- Dispersion prisms
- Displacement prisms
- Rotation prisms.
Gravitational force is given as

so here gravitational force will be given by above formula where the force between two objects depends on the mass of two objects and distance between them.
Now here since the tool is at finite distance from Astronaut and Moon, Sun, Earth
So all the above will exert gravitational force on the tool but the magnitude of force will be different as all of the above are of different masses and situated at different distance.
So all options are correct here
The Astronaut
The Moon
The Sun
The Earth