Answer - A. Low state
A TTL circuit acts as a current sink in the Low state
In the world of digital electronics, the phrase "current sinking and sourcing" refers to the direction in direct current (DC) flows between transistor-transistor logic (TTL) gates. It describes how regular current travels from the positive, also known as the sourcing end, to the ground, known as the sinking end.
Direct current often flows when two parts of a circuit source and sink current complete the circuit. When one gate feeds a signal to another gate in a TTL logic circuit, the sinking and sourcing actions happen at the same time.
The greatest current a pin may absorb through a load linked to an external supply is sink current. An NPN transistor offers a channel to the ground or zero potential and is used for sinking. A TTL circuit works as a current sink in the LOW state only.
Hence, Option (A) is the correct answer.