C

a,b,c be the length of each string
a+b+c=150 cm
we need find the value of a,b,c

stmt 1
let us assume a=20
so b+c=130

2 unknown values..
insuff

stmt 2
a+b=c
2c=150
c=75
2 unknown values..
insuff



combined
suff

3/2 meters=150 cm

a+b+c=150

stmt1,

20+a+b=150

a+b=130

No info about other 2 pieces.

Insufficient.

stmt2,

a+c=b

b=75

No info abt a,c.

Insufficient.

Combining 1 and 2,

Suppose C=20


a+c=b

a+20=b=75

a=55

Sufficient

Pick C

Given:
Let's take 3 pieces be of length a,b and c
Then a + b + c = 150

Stmt 1: a = 20 ------ you can assign any piece with length = 20
So b + C = 130
NOT SUFF

Stmt 2: a + b = c - NOT SUFF

USING BOTH STMT above

20 + b = c
b-c = -20 - eq1

b+c = 130 - eq 2

No Need to solve further, 2 eqn, two variable suficient to get the values.

Hence Ans = C