Formulate a multiple choice question related to the following topic.
The payment systems developed in the 19th century
Which of the following was a popular payment system developed in the 19th century?

a) Credit cards
b) Bitcoins
c) Paper checks
d) Mobile payments
Complete the following task based on the instruction and optional input provided.### Instruction:
Formulate a multiple choice question related to the following topic.

### Input:
The payment systems developed in the 19th century

### Output:
Which of the following was a popular payment system developed in the 19th century?

a) Credit cards
b) Bitcoins
c) Paper checks
d) Mobile payments