Answer:
LAOD = 6669.86 N
Explanation:
Given data:
width
thickness 
crack length 2c = 0.5 mm at centre of specimen

stress intensity factor = k will be


we know that

[c =0.5/2 = 2.5*10^{-4}]
K = 0.1724 Mpa m^{1/2} for 1000 load
if
then load will be




LAOD = 6669.86 N
I think it’s structural engineers but still check with the others
Answer: D. All of the choice A, B and C are correct.