(a) *↔* (iii)

because –6 + (+1) = –5, which lies between –11 and –4.

(b ) *↔*(i)

because +1 + (–11) = –10 which lies between –11 and –4.

(c) *↔* (iv)

because +7 + (–13) = –6 which lies between –11 and –4

(d) *↔*(ii)

because –2 + (–5) = –7 which lies between –11 and –4.