number of heads - half the number of tosses :

A. The bigger the number of tosses, the smaller the chance error is likely to be.

B. The bigger the number of tosses, the closer to 50% the percentage of heads is likely to be.

Then

a. Statement A is true but statement B is false

b. Statement B is true but statement A is false

c. Statements A and B are both true

d. Statements B and A are both false.