I need help with questions $18$ and $19$

$(4\%)$ Stacking fault energy is fairly high in pure $Cu(55\frac{mJ}{m^2}),$ but stacking fault energy decreases as $Zn$ is added to $Cu$ to form the solid$-$solution alloy called brass. In brass with $70wt.\%Cu$ and $30wt.\%Zn,$ stacking fault energy is only $14m\frac{J}{m^2}.$ Circle the letter of every statement below that correctly describes the changes that occur as stacking fault energy decreases? $($There may be $0,1,2,3,4,$ or $5$ correct answers below.$)$

a$)$ Dislocation cross slip occurs more easily and more often.

b$)$ Average spacing between $\frac{a}{6}($:$211$:$)-$type partial dislocation pairs increases.

c$)$ Partial dislocation pairs have a higher probability to intersect one another during cold work.

d$)$ Twins form more easily, and the concentration of twins increases.

e$)$ The metal's work$-$hardening rate increases.

$(4\%)$ Two TEM micrographs are shown below; one is a photograph of a cold$-$worked pure copper having a low stacking fault energy, and the other is a photograph of a cold$-$worked metal with a high stacking fault energy. Circle the image of the metal having a high stacking fault energy. The dislocations marked B on the right image below is edge or screw dislocation?