Answer:
b)−1×2×−3×4×−5 has a negative value.
Explanation:
Given expressions are a)−1×−2 b)−1×2×−3×4×−5 C) 1×−2×−3×−4×−5 d)1×−2×3×−4×5
Firstly we have to multiply the digits with digit then after minus sign.
So for a)−1×−2
Solution,

When two negative signs are multiplied with each other it gives a positive sign.
Both digits have a negative sign that means it gives a positive sign.
So the solution for 1st expression is

b)−1×2×−3×4×−5
Solution,

Here three digits have negative sign, two negative gives positive and then multiplied by negative gives negative.
So the solution for 2nd expression is
.
C) 1×−2×−3×−4×−5
Solution,

Here four digits have negative sign, two negative gives positive and again two negative gives positive means positive multiplied with positive gives positive.
So the solution for 3rd expression is
.
d)1×−2×3×−4×5
Solution,

Two digits have a negative sign that means it gives a positive sign.
So the solution for 4th expression is
.
Hence the correct option is b.