$(4)$ Bandwidth and delay $(1\mathrm{.}5+1\mathrm{.}5=3$ points$).$

$($a$)$ If you need to transfer a large file very quickly, which kind of link would you rather prefer, one with a higher or lower bandwidth? Why?

$($b$)$ If you need to support a highly interactive $($real$-$time$)$ voice call, which kind of link would you rather prefer, one with a higher or lower propagation delay? Why?