Explanation:

When a standing wave is formed, it consists of nodes and antinodes. The nodes are the points on the wave where the displacement is always zero, while the antinodes are the points on the wave where the displacement is maximum.

Standing Wave:
A standing wave is formed when two waves of the same frequency and amplitude traveling in opposite directions superpose. This superposition creates points along the wave where the displacement remains constant, resulting in nodes and antinodes.

Nodes and Antinodes:
- Nodes: These are the points on the wave where the displacement is always zero. At these points, the two waves are completely out of phase and cancel each other out, resulting in no displacement. Nodes occur at regular intervals along the wave.
- Antinodes: These are the points on the wave where the displacement is maximum. At these points, the two waves are perfectly in phase and reinforce each other, resulting in maximum displacement. Antinodes also occur at regular intervals, but they are located halfway between two adjacent nodes.

Distance between Maxima and Minima:
In a standing wave, the distance between two adjacent nodes or two adjacent antinodes is equal to half a wavelength (λ/2). This can be understood as follows:

- Between two adjacent nodes, there is a single antinode. Therefore, the distance between a node and the adjacent antinode is equal to half a wavelength (λ/2).
- Similarly, between two adjacent antinodes, there is a single node. Therefore, the distance between an antinode and the adjacent node is also equal to half a wavelength (λ/2).

Hence, the correct answer is option 'A': λ/4.

Summary:
The distance between the maxima (antinodes) and minima (nodes) of a standing wave is equal to half a wavelength (λ/2). Therefore, the correct answer is option 'A': λ/4.