[单选题]
A 4.00-kg cylinder ocxp0h + uijvec:7 pm0)f solid4m9y* fw: pbkv iron is supported by a string while submerged in water. What is the tension in the4 y9 wp*bkvf:m string? (The specific gravity of iron is 7.86.)
A. $2.50 \; N$
B. $19.6 \; N$
C. $23.7 \; N$
D. $34.2 \; N$
