The x$86-64$ calling convention uses two registers to manage procedure calls. Select the register that is always used for procedure calls.

Select one or more:

a$.\%$rbx

b$.\%$r$14$

c$.\%$r$9$

d$.\%$r$13$

e$.\%$r$11$

f$.\%$rsi

g$.\%$rbp

h$.\%$rcx

i$.\%$rax

j$.\%$r$12$

k$.\%$r$15$

l$.\%$r$10$

m$.\%$rsp

n$.\%$rdi

o$.\%$r$8$

p$.\%$rdx