function1: push (r4-r10, fp) add fp, sp, #28 add sp, sp, -4 // allocate local variable space add r4, r0,r1 // r4=r0+r1 add r5,r2, r3 // r5=r2+r3 add r6, r4, r5 // r6=r4+r5 str r6, (fp,#-32) // A=r4...

function1: push (r4-r10, fp)
add fp, sp, #28
add sp, sp, -4 // allocate local variable space
add r4, r0,r1 // r4=r0+r1
add r5,r2, r3 // r5=r2+r3
add r6, r4, r5 // r6=r4+r5
str r6, (fp,#-32) // A=r4
idr r0, (fp, #-32) // rl=A
sub sp, fp, #28
pop (r4-r10, fp)
bx lr
For the given ARM code, what is the minimal set of registers that must be saved by the routine
"function1"
a) {r4-r5}
b) {r4-r6}
c) {r4}
d) {rr4-r10}