In payback method one finds out *1 pointa. the period necessary to invest the cost of the systemb. the time required for the full benefits to accruec. the time at which benefits exceed costd. whether the system is able to payback amount invested

The payback method is a way of evaluating the investment in a project. Here's what each option means:

a. The period necessary to invest the cost of the system: This refers to the time it takes to put the initial investment into the project. This is not what the payback method calculates.

b. The time required for the full benefits to accrue: This refers to the time it takes for all the benefits or profits from the project to be realized. While the payback method does consider benefits, it doesn't specifically calculate the time for all benefits to accrue.

c. The time at which benefits exceed cost: This is what the payback method calculates. It's the point in time at which the cumulative cash inflows from the project equal the initial investment. After this point, the project is said to have 'paid back' its initial investment.

d. Whether the system is able to payback amount invested: While the payback method can give an indication of this (if the payback period is shorter than the project's life, it's likely that the project will pay back the initial investment), it's not the main purpose of the method. The main purpose is to calculate the payback period, not to make a definitive statement about whether the investment will be paid back.

So, the correct answer is c. The time at which benefits exceed cost.