Good evening sir.

Answer is 3rd option.

Explain it sir.

the resistance would be given as

R = ρl/A

here

RA = ρLA/AA = ρL / (L x L)

so,

RA =  ρ / L

and as thickness is same, equal to L

RB = ρLB/AB =  ρ2L/ (2Lx L)

so,

RB = ρ / L

thus, the ration will be

RA / RB = ( ρ / L) / ( ρ / L)

thus,

RA / RB = 1