Assume the initial price as p, and the corresponding quantity of demand is q. The increase of demand given the 10% of decline of price is dq, then,

(1-10%)p(q+dq) = (1+1%)pq,

which shows dq/q = 11/90

Then, the price elasticity of demand is

|e| = (dq/q)/(dp/p) = (11/90)/10% = 11/9 >1

so, A is the key.