Answer : 4. "Ability to think"
Explanation :

1. A computer is an electronic machine, which presents the required information or result (Output) by doing a specialized process according to a series of instructions (Program) given on the prescribed data (Input).

2. The following are the main characteristics of a computer.

(1) Speed

(2) Accuracy

(3) Economy

(4) Reliability

(5) Storage & Retrieval

(6) Repeated Processing Capacity