n a stationary wave,
A. Strain is maximum at antinodes.
B. Strain is maximum at nodes.
C. Strain is minimum at nodes.
D. Amplitude is zero at all points.

Hint - To give the answer of this question, we use the basics of waves, we read about in reflection of waves. First we see the definition of stationary wave; also we see the definition of amplitude, node and antinodes. Where amplitude is maximum and minimum in stationary waves. Stationary waves occur by resonance only at the natural frequencies of vibration of a medium.
Complete answer:
A stationary wave is a combination of two waves having equal amplitude and frequency but moving in opposite directions. Stationary wave also known as a standing wave, a standing wave is formed due to interference.
The amplitude of a wave is the distance from the centre lines to the top of a crest to the bottom of a trough. Amplitude is always measured in meters.
 Each stationary wave has points along with the medium that appears to be standing. Such points are known as nodes. Nodes have minimum amplitude.
Each stationary wave has points along with the medium which undergo maximum displacement during every vibration of wave. Such points are known as antinodes.
By definition, the node is the point where amplitude is minimum. Thus the strain is maximum at nodes in the stationary waves; so option B is correct.

Note – If a wave has greater amplitude then it is carrying more energy. Wavelength of a wave is the distance from the top of a crest to the top of the next crest similarly from bottom of a trough to bottom of the next trough. It measured in meters. The frequency of a wave is the number of waves passing through a point in a certain time. The S.I unit of frequency is hertz (HZ).