When C function starts from Y-axis, what does it indicate?

• Consumption is zero when income is zero
• Saving is positive when income is zero
• Saving is negative when income is zero
• Consumption is positive when income is zero

3 and 4

Consumption function starting from Y-axis indicates that there is autonomous consumption. It is that consumption which is independent to income, which means it happens at 0 level of income. This consumption is done with the past savings of the individual.