The concentrations of Tris and NaCl in 10x TBS are 200 mM Tris-HCl (pH 7.5) and 1.5 M NaCl. To prepare 1x TBS, we dilute the 10x solution by a factor of 10.
Therefore, the concentrations of Tris and NaCl in 1x TBS are:
a) Tris: 20 mM, NaCl: 0.15 M
b) Tris: 200 mM, NaCl: 1.5 M
c) Tris: 10 mM, NaCl: 0.15 M
d) Tris: 20 mM, NaCl: 1.5 M