A Circuit Joins Points $A, B, C$ And $D$ Into a Single Square Loop

A circuit joins points $A, B, C$ and $D$ into a single square loop. The voltage drops from $A$ to $B, B$ to $C$ , and $C$ to $\mathrm{D}$ , are $-5.2 \mathrm{~V}, 2.1 \mathrm{~V}$ , and $1.0 \mathrm{~V}$ , respectively. If one were to measure the voltage drop from $\mathrm{C}$ to $\mathrm{B}$ , one would obtain:

A) $-6.1 \mathrm{~V}$
B) $2.1 \mathrm{~V}$
C) $-2.1 \mathrm{~V}$
D) $-4.1 \mathrm{~V}$
E) $4.1 \mathrm{~V}$
F) $6.1 \mathrm{~V}$