According to price-time priority, which of the following outstanding orders will have execution priority at 11:31:22:

a.

A limit buy order placed at 11:31:12 with price $7.70 and volume of 784.

b.

A limit buy order placed at 11:31:14 with price $7.72 and volume of 864.

c.

A limit buy order placed at 11:31:16 with price $7.73 and volume of 937.

d.

A limit buy order placed at 11:31:14 with price $7.73 and volume of 864.