a$.$ Electronics $-$ solder for circuit boards

Desirable characteristics:

has rapid transformation between solid and liquid

$($i$.$e$.$ doesn't become mushy$)$

does not become too hot and damage components

Select one:

a$.0\mathrm{.}3\%$

b$.2\mathrm{.}5\%$

c$.38\mathrm{.}1\%$

d$.81\%$

e$.98\%$

full explanation please with workings