Which of the following is decade counter?

• The 74LS90 integrated circuit is basically a MOD-10 decade counter that produces a BCD output code.
• The letters LS indicate which subfamily the chip belongs to. LS (low-power Schottky) belongs to the TTL subfamily. 
• The 74LS90 consists of four master-slave JK flip-flops internally connected to provide a MOD-2 (count-to-2) counter and a MOD-5 (count-to-5) counter.
• The 74LS90 has one independent toggle JK flip-flop driven by the CLK A input and three toggles JK flip-flops that form an asynchronous counter driven by the CLK B input as shown.

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