The plot element that demonstrates the above theme is:
"the mother crab tried walking straight several times, but all her attempts were futile"
A theme is the element of a story or text that carries the dominant principle that the author intends to communicate.
In this case, the dominant idea is the mother crab could not live up to the standards that she had set for her son.
Learn more about theme at:
https://brainly.com/question/4008478
#SPJ4