Combine the two sentences into one with correct punctuation.
The study was complicated. It took the researcher four days to complete.
The study was complicated; it took the researcher four days to complete.
Complete the following task based on the instruction and optional input provided.### Instruction:
Combine the two sentences into one with correct punctuation.

### Input:
The study was complicated. It took the researcher four days to complete.

### Output:
The study was complicated; it took the researcher four days to complete.