Two identical wires are stretched by the same tension of $100 \mathrm{~N}$ and each emits a note of frequency $200 \mathrm{~Hz}$. If tension in one wire is increased by $1 \mathrm{~N}$, the number of beats heard per second when the wires are plucked is
(A) 2
(B) 1
(C) 3
(D) 4