Bond $1$: Coupon rate $=3\%,$ YTM $=2\mathrm{.}5\%$

Bond $2$: Coupon rate $=3\%,$ YTM $=3\%$

Bond $3$: Coupon rate $=3\%,$ YTM $=2\mathrm{.}75\%$

Bond $4$: Coupon rate $=3\%,$ YTM $=3\mathrm{.}25\%$

Which of the bonds is selling at par?

a$.)$

Bond $3$

b$.)$

Bond $1$

c$.)$

Bond $4$

d$.)$

Bond $2$