We are given the following two vectors

(a) Greater x component
Vector A (1.2 m) has a greater x component as compared to vector B (-3.4 m) because vector A is positive and vector B is negative.
Vector A has a greater x component
(b) Greater magnitude
Vector B (3.4 m) has a greater magnitude as compared to vector A (1.2 m) because the absolute value of vector B is greater than the absolute value of vector A.

Vector B has a greater magnitude.