Can the given lengths be the sides of a right triangle?
7cm, 40cm, 41cm

A right triangle has legnths that have a special relationship to each other
if you have legs legnth a and b and hypotonuse legnth c
a^2+b^2=c^2  yeilds a true statement

so the hypotonuse is normally the longest side so 41 cm is the hypotonuse
c=41

a=7
b=40

subsitute
7^2+40^2=41^2
49+1600=1681
1649=1681
false

this is not a right triangle

The answer to your question is the last one