Stationary waves are formed when:
A. Two waves of equal amplitude and equal frequency travel along the same path in the opposite direction.
B. Two waves of equal wavelength and amplitude travel along the same path with speeds in opposite directions.
C. Two waves of equal wavelength and equal phase travel along the same path with same speed.
D. Two waves of equal amplitude and speed travel along the same path in opposite directions.

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Hint: Wave is a disturbance or we can say change from equilibrium of one or more quantities, sometimes as described by a differential equation. In physical waves, a minimum of two field quantities within the wave medium are involved. Waves are often periodic, during which case those quantities oscillate repeatedly about an equilibrium (resting) value at some frequency.

Complete step by step answer:
A standing wave also called a stationary wave is a wave that is still during a constant position. It can arise during a stationary medium as a result of interference between two waves of equal wavelengths, travelling along an equivalent path but in opposite directions. they ought to have almost the same amplitude. Stationary waves are characterised by the confinement of a wave disturbance between two rigid boundaries. This means, the wave does not move forward or backward in a medium (does not advance), it remains steady at its place. Therefore, they are called “stationary waves or standing waves”. Certain points in the region in which the wave exists have maximum amplitude, called as anti-nodes and at certain points the amplitude is minimum or zero, called as nodes.
So, the correct answer is “Option B”.

Additional Information: The types of waves most ordinarily studied in classical physics are mechanical and electromagnetic. during a mechanical wave, stress and strain fields oscillate a few mechanical equilibria. A mechanical wave is said to be a local strain in some physical medium that propagates from particle to particle by creating local stresses that cause strain in neighbouring particles too. For instance, sound waves are variations of the local pressure and particle motion that propagate through the medium. Other samples of mechanical waves are seismic waves, gravity waves, surface waves, string vibrations (standing waves), and vortices. In an electromagnetic radiation (such as light) energy is interchanged between the electrical and magnetic fields which sustain propagation of a wave involving these fields consistent with Maxwell's equations. Electromagnetic waves can travel through a vacuum and through some dielectric media.

Note: In a stationary wave, adjacent points are in phase with one another (sections of the wave flap up and down together), in order that points of a specific phase remain at a hard and fast location as time progresses.Antinodes are points on a standing wave that oscillate with maximum amplitude. Nodes are points of zero amplitude.